diff --git a/Cargo.lock b/Cargo.lock
index 0b584dc9a2e..45d34bfcd8f 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -5645,9 +5645,9 @@ dependencies = [
 
 [[package]]
 name = "serde_json"
-version = "1.0.97"
+version = "1.0.107"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "bdf3bf93142acad5821c99197022e170842cdbc1c30482b98750c688c640842a"
+checksum = "6b420ce6e3d8bd882e9b243c6eed35dbc9a6110c9769e74b584e0d68d1f20c65"
 dependencies = [
  "itoa",
  "ryu",
@@ -7640,6 +7640,7 @@ name = "zksync_basic_types"
 version = "0.1.0"
 dependencies = [
  "serde",
+ "serde_json",
  "web3",
 ]
 
diff --git a/core/bin/external_node/src/config/mod.rs b/core/bin/external_node/src/config/mod.rs
index 35b1e91bc08..66f4e54ff57 100644
--- a/core/bin/external_node/src/config/mod.rs
+++ b/core/bin/external_node/src/config/mod.rs
@@ -52,13 +52,14 @@ impl RemoteENConfig {
             .get_main_contract()
             .await
             .context("Failed to fetch L1 contract address")?;
-        let l2_chain_id = L2ChainId(
+        let l2_chain_id = L2ChainId::try_from(
             client
                 .chain_id()
                 .await
                 .context("Failed to fetch L2 chain ID")?
-                .as_u64() as u16,
-        );
+                .as_u64(),
+        )
+        .unwrap();
         let l1_chain_id = L1ChainId(
             client
                 .l1_chain_id()
@@ -396,14 +397,14 @@ impl ExternalNodeConfig {
             .await
             .context("Unable to check L1 chain ID through the configured L1 client")?;
 
-        let l2_chain_id: u16 = env_var("EN_L2_CHAIN_ID");
+        let l2_chain_id: L2ChainId = env_var("EN_L2_CHAIN_ID");
         let l1_chain_id: u64 = env_var("EN_L1_CHAIN_ID");
-        if l2_chain_id != remote.l2_chain_id.0 {
+        if l2_chain_id != remote.l2_chain_id {
             anyhow::bail!(
                 "Configured L2 chain id doesn't match the one from main node.
                 Make sure your configuration is correct and you are corrected to the right main node.
-                Main node L2 chain id: {}. Local config value: {}",
-                remote.l2_chain_id.0, l2_chain_id
+                Main node L2 chain id: {:?}. Local config value: {:?}",
+                remote.l2_chain_id, l2_chain_id
             );
         }
         if l1_chain_id != remote.l1_chain_id.0 {
diff --git a/core/bin/system-constants-generator/src/utils.rs b/core/bin/system-constants-generator/src/utils.rs
index afb00b5cda7..d55a73d4e8f 100644
--- a/core/bin/system-constants-generator/src/utils.rs
+++ b/core/bin/system-constants-generator/src/utils.rs
@@ -92,7 +92,7 @@ pub(super) fn get_l2_tx(contract_address: Address, signer: &H256, pubdata_price:
             gas_per_pubdata_limit: pubdata_price.into(),
         },
         U256::from(0),
-        L2ChainId(270),
+        L2ChainId::from(270),
         signer,
         None,
         Default::default(),
diff --git a/core/lib/basic_types/Cargo.toml b/core/lib/basic_types/Cargo.toml
index e96dd0c0ce2..4e8d8af8c15 100644
--- a/core/lib/basic_types/Cargo.toml
+++ b/core/lib/basic_types/Cargo.toml
@@ -12,3 +12,4 @@ categories = ["cryptography"]
 [dependencies]
 web3 = { version= "0.19.0", default-features = false, features = ["http-rustls-tls", "test", "signing"] }
 serde = { version = "1.0", features = ["derive"] }
+serde_json = "1.0"
diff --git a/core/lib/basic_types/src/lib.rs b/core/lib/basic_types/src/lib.rs
index a8f7cacbae5..3223dfddf59 100644
--- a/core/lib/basic_types/src/lib.rs
+++ b/core/lib/basic_types/src/lib.rs
@@ -7,7 +7,7 @@ mod macros;
 
 pub mod network;
 
-use serde::{Deserialize, Serialize};
+use serde::{de, Deserialize, Deserializer, Serialize};
 use std::convert::{Infallible, TryFrom, TryInto};
 use std::fmt;
 use std::num::ParseIntError;
@@ -76,6 +76,85 @@ impl TryFrom<U256> for AccountTreeId {
     }
 }
 
+/// ChainId in the ZkSync network.
+#[derive(Copy, Clone, Debug, Serialize, PartialEq, Eq, PartialOrd, Ord, Hash)]
+pub struct L2ChainId(u64);
+
+impl<'de> Deserialize<'de> for L2ChainId {
+    fn deserialize<D>(deserializer: D) -> Result<Self, D::Error>
+    where
+        D: Deserializer<'de>,
+    {
+        let s: String = Deserialize::deserialize(deserializer)?;
+        s.parse().map_err(de::Error::custom)
+    }
+}
+
+impl FromStr for L2ChainId {
+    type Err = String;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        // Parse the string as a U64
+        // try to parse as decimal first
+        let number = match U64::from_dec_str(s) {
+            Ok(u) => u,
+            Err(_) => {
+                // try to parse as hex
+                s.parse::<U64>()
+                    .map_err(|err| format!("Failed to parse L2ChainId: Err {err}"))?
+            }
+        };
+
+        if number.as_u64() > L2ChainId::max().0 {
+            return Err(format!("Too big chain ID. MAX: {}", L2ChainId::max().0));
+        }
+        Ok(L2ChainId(number.as_u64()))
+    }
+}
+
+impl L2ChainId {
+    /// The maximum value of the L2 chain ID.
+    // 2^53 - 1 is a max safe integer in JS. In ethereum JS libs chain ID should be the safe integer.
+    // Next arithmetic operation: subtract 36 and divide by 2 comes from `v` calculation:
+    // v = 2*chainId + 36, that should be save integer as well.
+    const MAX: u64 = ((1 << 53) - 1 - 36) / 2;
+
+    pub fn max() -> Self {
+        Self(Self::MAX)
+    }
+
+    pub fn as_u64(&self) -> u64 {
+        self.0
+    }
+}
+
+impl Default for L2ChainId {
+    fn default() -> Self {
+        Self(270)
+    }
+}
+
+impl TryFrom<u64> for L2ChainId {
+    type Error = String;
+
+    fn try_from(val: u64) -> Result<Self, Self::Error> {
+        if val > L2ChainId::max().0 {
+            return Err(format!(
+                "Cannot convert given value {} into L2ChainId. It's greater than MAX: {},",
+                val,
+                L2ChainId::max().0,
+            ));
+        }
+        Ok(Self(val))
+    }
+}
+
+impl From<u32> for L2ChainId {
+    fn from(value: u32) -> Self {
+        Self(value as u64)
+    }
+}
+
 basic_type!(
     /// zkSync network block sequential index.
     MiniblockNumber,
@@ -112,12 +191,6 @@ basic_type!(
     u64
 );
 
-basic_type!(
-    /// ChainId in the ZkSync network.
-    L2ChainId,
-    u16
-);
-
 #[allow(clippy::derivable_impls)]
 impl Default for MiniblockNumber {
     fn default() -> Self {
@@ -139,15 +212,78 @@ impl Default for L1BlockNumber {
     }
 }
 
-impl Default for L2ChainId {
-    fn default() -> Self {
-        Self(270)
-    }
-}
-
 #[allow(clippy::derivable_impls)]
 impl Default for PriorityOpId {
     fn default() -> Self {
         Self(0)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use serde_json::from_str;
+
+    #[test]
+    fn test_from_str_valid_decimal() {
+        let input = "42";
+        let result = L2ChainId::from_str(input);
+        assert_eq!(result.unwrap().as_u64(), 42);
+    }
+
+    #[test]
+    fn test_from_str_valid_hexadecimal() {
+        let input = "0x2A";
+        let result = L2ChainId::from_str(input);
+        assert_eq!(result.unwrap().as_u64(), 42);
+    }
+
+    #[test]
+    fn test_from_str_too_big_chain_id() {
+        let input = "18446744073709551615"; // 2^64 - 1
+        let result = L2ChainId::from_str(input);
+        assert_eq!(
+            result,
+            Err(format!("Too big chain ID. MAX: {}", L2ChainId::max().0))
+        );
+    }
+
+    #[test]
+    fn test_from_str_invalid_input() {
+        let input = "invalid"; // Invalid input that cannot be parsed as a number
+        let result = L2ChainId::from_str(input);
+
+        assert!(result.is_err());
+        assert!(result
+            .unwrap_err()
+            .contains("Failed to parse L2ChainId: Err "));
+    }
+
+    #[test]
+    fn test_deserialize_valid_decimal() {
+        let input_json = "\"42\"";
+
+        let result: Result<L2ChainId, _> = from_str(input_json);
+        assert_eq!(result.unwrap().as_u64(), 42);
+    }
+
+    #[test]
+    fn test_deserialize_valid_hex() {
+        let input_json = "\"0x2A\"";
+
+        let result: Result<L2ChainId, _> = from_str(input_json);
+        assert_eq!(result.unwrap().as_u64(), 42);
+    }
+
+    #[test]
+    fn test_deserialize_invalid() {
+        let input_json = "\"invalid\"";
+
+        let result: Result<L2ChainId, serde_json::Error> = from_str(input_json);
+        assert!(result.is_err());
+        assert!(result
+            .unwrap_err()
+            .to_string()
+            .contains("Failed to parse L2ChainId: Err Invalid character "));
+    }
+}
diff --git a/core/lib/config/src/configs/chain.rs b/core/lib/config/src/configs/chain.rs
index 3e680b435e4..afb92871694 100644
--- a/core/lib/config/src/configs/chain.rs
+++ b/core/lib/config/src/configs/chain.rs
@@ -5,7 +5,7 @@ use serde::Deserialize;
 use std::time::Duration;
 // Local uses
 use zksync_basic_types::network::Network;
-use zksync_basic_types::{Address, H256};
+use zksync_basic_types::{Address, L2ChainId, H256};
 use zksync_contracts::BaseSystemContractsHashes;
 
 use super::envy_load;
@@ -47,7 +47,7 @@ pub struct NetworkConfig {
     pub zksync_network: String,
     /// ID of current zkSync network treated as ETH network ID.
     /// Used to distinguish zkSync from other Web3-capable networks.
-    pub zksync_network_id: u16,
+    pub zksync_network_id: L2ChainId,
 }
 
 impl NetworkConfig {
@@ -202,7 +202,7 @@ mod tests {
             network: NetworkConfig {
                 network: "localhost".parse().unwrap(),
                 zksync_network: "localhost".to_string(),
-                zksync_network_id: 270,
+                zksync_network_id: L2ChainId::from(270),
             },
             state_keeper: StateKeeperConfig {
                 transaction_slots: 50,
diff --git a/core/lib/dal/src/blocks_web3_dal.rs b/core/lib/dal/src/blocks_web3_dal.rs
index 301f6940d1a..03ec1c1930f 100644
--- a/core/lib/dal/src/blocks_web3_dal.rs
+++ b/core/lib/dal/src/blocks_web3_dal.rs
@@ -623,7 +623,7 @@ mod tests {
         for block_id in block_ids {
             let block = conn
                 .blocks_web3_dal()
-                .get_block_by_web3_block_id(block_id, false, L2ChainId(270))
+                .get_block_by_web3_block_id(block_id, false, L2ChainId::from(270))
                 .await;
             let block = block.unwrap().unwrap();
             assert!(block.transactions.is_empty());
@@ -650,7 +650,7 @@ mod tests {
         for block_id in non_existing_block_ids {
             let block = conn
                 .blocks_web3_dal()
-                .get_block_by_web3_block_id(block_id, false, L2ChainId(270))
+                .get_block_by_web3_block_id(block_id, false, L2ChainId::from(270))
                 .await;
             assert!(block.unwrap().is_none());
 
diff --git a/core/lib/dal/src/models/storage_transaction.rs b/core/lib/dal/src/models/storage_transaction.rs
index 738cf3356f3..554d33649f2 100644
--- a/core/lib/dal/src/models/storage_transaction.rs
+++ b/core/lib/dal/src/models/storage_transaction.rs
@@ -389,7 +389,7 @@ impl<'r> FromRow<'r, PgRow> for StorageApiTransaction {
                     .unwrap_or_default()
                     .map(U64::from),
                 access_list: None,
-                chain_id: U256::from(0),
+                chain_id: 0,
                 l1_batch_number: db_row
                     .try_get::<i64, &str>("l1_batch_number_tx")
                     .ok()
@@ -502,7 +502,7 @@ pub fn web3_transaction_select_sql() -> &'static str {
 
 pub fn extract_web3_transaction(db_row: PgRow, chain_id: L2ChainId) -> api::Transaction {
     let mut storage_api_tx = StorageApiTransaction::from_row(&db_row).unwrap();
-    storage_api_tx.inner_api_transaction.chain_id = U256::from(chain_id.0);
+    storage_api_tx.inner_api_transaction.chain_id = chain_id.as_u64();
     storage_api_tx.into()
 }
 
diff --git a/core/lib/dal/src/tests/mod.rs b/core/lib/dal/src/tests/mod.rs
index 3f39f98a45a..fecd33f4761 100644
--- a/core/lib/dal/src/tests/mod.rs
+++ b/core/lib/dal/src/tests/mod.rs
@@ -59,7 +59,7 @@ pub(crate) fn mock_l2_transaction() -> L2Tx {
         zksync_types::Nonce(0),
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &H256::random(),
         None,
         Default::default(),
diff --git a/core/lib/dal/src/transactions_web3_dal.rs b/core/lib/dal/src/transactions_web3_dal.rs
index c9a6ee8bf76..8ad983a2218 100644
--- a/core/lib/dal/src/transactions_web3_dal.rs
+++ b/core/lib/dal/src/transactions_web3_dal.rs
@@ -417,7 +417,7 @@ mod tests {
         for transaction_id in transaction_ids {
             let web3_tx = conn
                 .transactions_web3_dal()
-                .get_transaction(transaction_id, L2ChainId(270))
+                .get_transaction(transaction_id, L2ChainId::from(270))
                 .await;
             let web3_tx = web3_tx.unwrap().unwrap();
             assert_eq!(web3_tx.hash, tx_hash);
@@ -431,7 +431,7 @@ mod tests {
         for transaction_id in transactions_with_bogus_index {
             let web3_tx = conn
                 .transactions_web3_dal()
-                .get_transaction(transaction_id, L2ChainId(270))
+                .get_transaction(transaction_id, L2ChainId::from(270))
                 .await;
             assert!(web3_tx.unwrap().is_none());
         }
@@ -448,7 +448,7 @@ mod tests {
         for transaction_id in transactions_with_bogus_block {
             let web3_tx = conn
                 .transactions_web3_dal()
-                .get_transaction(transaction_id, L2ChainId(270))
+                .get_transaction(transaction_id, L2ChainId::from(270))
                 .await;
             assert!(web3_tx.unwrap().is_none());
         }
diff --git a/core/lib/state/src/in_memory.rs b/core/lib/state/src/in_memory.rs
index 3ae72a9f4e9..e44187e34d9 100644
--- a/core/lib/state/src/in_memory.rs
+++ b/core/lib/state/src/in_memory.rs
@@ -9,7 +9,7 @@ use zksync_types::{
 use zksync_utils::u256_to_h256;
 
 /// Network ID we use by defailt for in memory storage.
-pub const IN_MEMORY_STORAGE_DEFAULT_NETWORK_ID: u16 = 270;
+pub const IN_MEMORY_STORAGE_DEFAULT_NETWORK_ID: u32 = 270;
 
 /// In-memory storage.
 #[derive(Debug, Default)]
@@ -22,7 +22,7 @@ impl InMemoryStorage {
     /// Constructs a storage that contains system smart contracts.
     pub fn with_system_contracts(bytecode_hasher: impl Fn(&[u8]) -> H256) -> Self {
         Self::with_system_contracts_and_chain_id(
-            L2ChainId(IN_MEMORY_STORAGE_DEFAULT_NETWORK_ID),
+            L2ChainId::from(IN_MEMORY_STORAGE_DEFAULT_NETWORK_ID),
             bytecode_hasher,
         )
     }
diff --git a/core/lib/test_account/src/lib.rs b/core/lib/test_account/src/lib.rs
index 9c94e3f49cf..509402b7b6b 100644
--- a/core/lib/test_account/src/lib.rs
+++ b/core/lib/test_account/src/lib.rs
@@ -77,7 +77,7 @@ impl Account {
             nonce,
             fee.unwrap_or_else(|| self.default_fee()),
             value,
-            L2ChainId(270),
+            L2ChainId::default(),
             &self.private_key,
             factory_deps,
             Default::default(),
diff --git a/core/lib/types/src/api/mod.rs b/core/lib/types/src/api/mod.rs
index c9b157c6629..6c65356081b 100644
--- a/core/lib/types/src/api/mod.rs
+++ b/core/lib/types/src/api/mod.rs
@@ -505,7 +505,7 @@ pub struct Transaction {
     pub max_priority_fee_per_gas: Option<U256>,
     /// Id of the current chain
     #[serde(rename = "chainId")]
-    pub chain_id: U256,
+    pub chain_id: u64,
     /// Number of the l1 batch this transaction was included within.
     #[serde(
         rename = "l1BatchNumber",
diff --git a/core/lib/types/src/l2/mod.rs b/core/lib/types/src/l2/mod.rs
index 973c5a30b10..b1ef8ca07a7 100644
--- a/core/lib/types/src/l2/mod.rs
+++ b/core/lib/types/src/l2/mod.rs
@@ -93,7 +93,7 @@ impl L2TxCommonData {
         self.input = Some(InputData { hash, data: input })
     }
 
-    pub fn extract_chain_id(&self) -> Option<u16> {
+    pub fn extract_chain_id(&self) -> Option<u64> {
         let bytes = self.input_data()?;
         let chain_id = match bytes.first() {
             Some(x) if *x >= 0x80 => {
@@ -226,7 +226,7 @@ impl L2Tx {
     pub fn get_rlp_bytes(&self, chain_id: L2ChainId) -> Bytes {
         let mut rlp_stream = RlpStream::new();
         let tx: TransactionRequest = self.clone().into();
-        tx.rlp(&mut rlp_stream, chain_id.0, None);
+        tx.rlp(&mut rlp_stream, chain_id.as_u64(), None);
         Bytes(rlp_stream.as_raw().to_vec())
     }
 
@@ -329,7 +329,7 @@ impl From<L2Tx> for TransactionRequest {
             transaction_type: None,
             access_list: None,
             eip712_meta: None,
-            chain_id: tx.common_data.extract_chain_id().unwrap_or_default().into(),
+            chain_id: tx.common_data.extract_chain_id(),
         };
         match tx_type as u8 {
             LEGACY_TX_TYPE => {}
@@ -389,7 +389,7 @@ impl From<L2Tx> for api::Transaction {
 
         Self {
             hash: tx.hash(),
-            chain_id: tx.common_data.extract_chain_id().unwrap_or_default().into(),
+            chain_id: tx.common_data.extract_chain_id().unwrap_or_default(),
             nonce: U256::from(tx.common_data.nonce.0),
             from: Some(tx.common_data.initiator_address),
             to: Some(tx.recipient_account()),
diff --git a/core/lib/types/src/storage/mod.rs b/core/lib/types/src/storage/mod.rs
index b1ed25dad97..bf790b58d3d 100644
--- a/core/lib/types/src/storage/mod.rs
+++ b/core/lib/types/src/storage/mod.rs
@@ -103,7 +103,7 @@ pub fn get_system_context_init_logs(chain_id: L2ChainId) -> Vec<StorageLog> {
     vec![
         StorageLog::new_write_log(
             get_system_context_key(SYSTEM_CONTEXT_CHAIN_ID_POSITION),
-            H256::from_low_u64_be(chain_id.0 as u64),
+            H256::from_low_u64_be(chain_id.as_u64()),
         ),
         StorageLog::new_write_log(
             get_system_context_key(SYSTEM_CONTEXT_BLOCK_GAS_LIMIT_POSITION),
diff --git a/core/lib/types/src/transaction_request.rs b/core/lib/types/src/transaction_request.rs
index 0516081434d..c9af634c3e4 100644
--- a/core/lib/types/src/transaction_request.rs
+++ b/core/lib/types/src/transaction_request.rs
@@ -168,7 +168,7 @@ pub enum SerializationTransactionError {
     #[error("invalid signature")]
     MalformedSignature,
     #[error("wrong chain id {}", .0.unwrap_or_default())]
-    WrongChainId(Option<u16>),
+    WrongChainId(Option<u64>),
     #[error("malformed paymaster params")]
     MalforedPaymasterParams,
     #[error("factory dependency #{0} is invalid: {1}")]
@@ -233,7 +233,7 @@ pub struct TransactionRequest {
     pub eip712_meta: Option<Eip712Meta>,
     /// Chain ID
     #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub chain_id: Option<u16>,
+    pub chain_id: Option<u64>,
 }
 
 #[derive(Default, Serialize, Deserialize, Clone, PartialEq, Debug, Eq)]
@@ -426,7 +426,7 @@ impl TransactionRequest {
 
     pub fn get_signed_bytes(&self, signature: &PackedEthSignature, chain_id: L2ChainId) -> Vec<u8> {
         let mut rlp = RlpStream::new();
-        self.rlp(&mut rlp, *chain_id, Some(signature));
+        self.rlp(&mut rlp, chain_id.as_u64(), Some(signature));
         let mut data = rlp.out().to_vec();
         if let Some(tx_type) = self.transaction_type {
             data.insert(0, tx_type.as_u64() as u8);
@@ -438,7 +438,7 @@ impl TransactionRequest {
         self.transaction_type.is_none() || self.transaction_type == Some(LEGACY_TX_TYPE.into())
     }
 
-    pub fn rlp(&self, rlp: &mut RlpStream, chain_id: u16, signature: Option<&PackedEthSignature>) {
+    pub fn rlp(&self, rlp: &mut RlpStream, chain_id: u64, signature: Option<&PackedEthSignature>) {
         rlp.begin_unbounded_list();
 
         match self.transaction_type {
@@ -553,7 +553,7 @@ impl TransactionRequest {
 
     pub fn from_bytes(
         bytes: &[u8],
-        chain_id: u16,
+        chain_id: L2ChainId,
     ) -> Result<(Self, H256), SerializationTransactionError> {
         let rlp;
         let mut tx = match bytes.first() {
@@ -567,7 +567,7 @@ impl TransactionRequest {
                 let v = rlp.val_at(6)?;
                 let (_, tx_chain_id) = PackedEthSignature::unpack_v(v)
                     .map_err(|_| SerializationTransactionError::MalformedSignature)?;
-                if tx_chain_id.is_some() && tx_chain_id != Some(chain_id) {
+                if tx_chain_id.is_some() && tx_chain_id != Some(chain_id.as_u64()) {
                     return Err(SerializationTransactionError::WrongChainId(tx_chain_id));
                 }
                 Self {
@@ -592,7 +592,7 @@ impl TransactionRequest {
                 }
 
                 let tx_chain_id = rlp.val_at(0).ok();
-                if tx_chain_id != Some(chain_id) {
+                if tx_chain_id != Some(chain_id.as_u64()) {
                     return Err(SerializationTransactionError::WrongChainId(tx_chain_id));
                 }
                 Self {
@@ -613,7 +613,7 @@ impl TransactionRequest {
                     ));
                 }
                 let tx_chain_id = rlp.val_at(10).ok();
-                if tx_chain_id.is_some() && tx_chain_id != Some(chain_id) {
+                if tx_chain_id.is_some() && tx_chain_id != Some(chain_id.as_u64()) {
                     return Err(SerializationTransactionError::WrongChainId(tx_chain_id));
                 }
 
@@ -658,21 +658,20 @@ impl TransactionRequest {
             None => tx.recover_default_signer(default_signed_message).ok(),
         };
 
-        let hash =
-            tx.get_tx_hash_with_signed_message(&default_signed_message, L2ChainId(chain_id))?;
+        let hash = tx.get_tx_hash_with_signed_message(&default_signed_message, chain_id)?;
 
         Ok((tx, hash))
     }
 
     fn get_default_signed_message(
         &self,
-        chain_id: Option<u16>,
+        chain_id: Option<u64>,
     ) -> Result<H256, SerializationTransactionError> {
         if self.is_eip712_tx() {
             let tx_chain_id =
                 chain_id.ok_or(SerializationTransactionError::WrongChainId(chain_id))?;
             Ok(PackedEthSignature::typed_data_to_signed_bytes(
-                &Eip712Domain::new(L2ChainId(tx_chain_id)),
+                &Eip712Domain::new(L2ChainId::try_from(tx_chain_id).unwrap()),
                 self,
             ))
         } else {
@@ -707,7 +706,7 @@ impl TransactionRequest {
     }
 
     pub fn get_tx_hash(&self, chain_id: L2ChainId) -> Result<H256, SerializationTransactionError> {
-        let default_signed_message = self.get_default_signed_message(Some(chain_id.0))?;
+        let default_signed_message = self.get_default_signed_message(Some(chain_id.as_u64()))?;
         self.get_tx_hash_with_signed_message(&default_signed_message, chain_id)
     }
 
@@ -979,8 +978,11 @@ mod tests {
             access_list: None,
         };
         let signed_tx = accounts.sign_transaction(tx.clone(), &key).await.unwrap();
-        let (tx2, _) =
-            TransactionRequest::from_bytes(signed_tx.raw_transaction.0.as_slice(), 270).unwrap();
+        let (tx2, _) = TransactionRequest::from_bytes(
+            signed_tx.raw_transaction.0.as_slice(),
+            L2ChainId::from(270),
+        )
+        .unwrap();
         assert_eq!(tx.gas, tx2.gas);
         assert_eq!(tx.gas_price.unwrap(), tx2.gas_price);
         assert_eq!(tx.nonce.unwrap(), tx2.nonce);
@@ -1013,16 +1015,13 @@ mod tests {
         let mut rlp = RlpStream::new();
         tx.rlp(&mut rlp, 270, Some(&signature));
         let data = rlp.out().to_vec();
-        let (tx2, _) = TransactionRequest::from_bytes(&data, 270).unwrap();
+        let (tx2, _) = TransactionRequest::from_bytes(&data, L2ChainId::from(270)).unwrap();
         assert_eq!(tx.gas, tx2.gas);
         assert_eq!(tx.gas_price, tx2.gas_price);
         assert_eq!(tx.nonce, tx2.nonce);
         assert_eq!(tx.input, tx2.input);
         assert_eq!(tx.value, tx2.value);
-        assert_eq!(
-            tx2.v.unwrap().as_u32() as u16,
-            signature.v_with_chain_id(270)
-        );
+        assert_eq!(tx2.v.unwrap().as_u64(), signature.v_with_chain_id(270));
         assert_eq!(tx2.s.unwrap(), signature.s().into());
         assert_eq!(tx2.r.unwrap(), signature.r().into());
         assert_eq!(address, tx2.from.unwrap());
@@ -1056,8 +1055,10 @@ mod tests {
             ..Default::default()
         };
 
-        let msg =
-            PackedEthSignature::typed_data_to_signed_bytes(&Eip712Domain::new(L2ChainId(270)), &tx);
+        let msg = PackedEthSignature::typed_data_to_signed_bytes(
+            &Eip712Domain::new(L2ChainId::from(270)),
+            &tx,
+        );
         let signature = PackedEthSignature::sign_raw(&private_key, &msg).unwrap();
 
         let mut rlp = RlpStream::new();
@@ -1069,7 +1070,7 @@ mod tests {
         tx.r = Some(U256::from_big_endian(signature.r()));
         tx.s = Some(U256::from_big_endian(signature.s()));
 
-        let (tx2, _) = TransactionRequest::from_bytes(&data, 270).unwrap();
+        let (tx2, _) = TransactionRequest::from_bytes(&data, L2ChainId::from(270)).unwrap();
 
         assert_eq!(tx, tx2);
     }
@@ -1098,14 +1099,15 @@ mod tests {
             chain_id: Some(270),
             ..Default::default()
         };
-        let domain = Eip712Domain::new(L2ChainId(270));
+        let domain = Eip712Domain::new(L2ChainId::from(270));
         let signature =
             PackedEthSignature::sign_typed_data(&private_key, &domain, &transaction_request)
                 .unwrap();
 
-        let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId(270));
+        let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId::from(270));
 
-        let (decoded_tx, _) = TransactionRequest::from_bytes(encoded_tx.as_slice(), 270).unwrap();
+        let (decoded_tx, _) =
+            TransactionRequest::from_bytes(encoded_tx.as_slice(), L2ChainId::from(270)).unwrap();
         let recovered_signer = decoded_tx.from.unwrap();
         assert_eq!(address, recovered_signer);
     }
@@ -1137,14 +1139,15 @@ mod tests {
             chain_id: Some(270),
             ..Default::default()
         };
-        let domain = Eip712Domain::new(L2ChainId(270));
+        let domain = Eip712Domain::new(L2ChainId::from(270));
         let signature =
             PackedEthSignature::sign_typed_data(&private_key, &domain, &transaction_request)
                 .unwrap();
 
-        let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId(270));
+        let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId::from(270));
 
-        let decoded_tx = TransactionRequest::from_bytes(encoded_tx.as_slice(), 272);
+        let decoded_tx =
+            TransactionRequest::from_bytes(encoded_tx.as_slice(), L2ChainId::from(272));
         assert_eq!(
             decoded_tx,
             Err(SerializationTransactionError::WrongChainId(Some(270)))
@@ -1184,7 +1187,8 @@ mod tests {
         let mut data = rlp.out().to_vec();
         data.insert(0, EIP_1559_TX_TYPE);
 
-        let (decoded_tx, _) = TransactionRequest::from_bytes(data.as_slice(), 270).unwrap();
+        let (decoded_tx, _) =
+            TransactionRequest::from_bytes(data.as_slice(), L2ChainId::from(270)).unwrap();
         let recovered_signer = decoded_tx.from.unwrap();
         assert_eq!(address, recovered_signer);
     }
@@ -1221,7 +1225,7 @@ mod tests {
         let mut data = rlp.out().to_vec();
         data.insert(0, EIP_1559_TX_TYPE);
 
-        let decoded_tx = TransactionRequest::from_bytes(data.as_slice(), 270);
+        let decoded_tx = TransactionRequest::from_bytes(data.as_slice(), L2ChainId::from(270));
         assert_eq!(
             decoded_tx,
             Err(SerializationTransactionError::WrongChainId(Some(272)))
@@ -1261,7 +1265,7 @@ mod tests {
         let mut data = rlp.out().to_vec();
         data.insert(0, EIP_1559_TX_TYPE);
 
-        let res = TransactionRequest::from_bytes(data.as_slice(), 270);
+        let res = TransactionRequest::from_bytes(data.as_slice(), L2ChainId::from(270));
         assert_eq!(
             res,
             Err(SerializationTransactionError::AccessListsNotSupported)
@@ -1298,7 +1302,7 @@ mod tests {
         let mut data = rlp.out().to_vec();
         data.insert(0, EIP_2930_TX_TYPE);
 
-        let res = TransactionRequest::from_bytes(data.as_slice(), 270);
+        let res = TransactionRequest::from_bytes(data.as_slice(), L2ChainId::from(270));
         assert_eq!(
             res,
             Err(SerializationTransactionError::AccessListsNotSupported)
@@ -1419,8 +1423,10 @@ mod tests {
             ..Default::default()
         };
 
-        let msg =
-            PackedEthSignature::typed_data_to_signed_bytes(&Eip712Domain::new(L2ChainId(270)), &tx);
+        let msg = PackedEthSignature::typed_data_to_signed_bytes(
+            &Eip712Domain::new(L2ChainId::from(270)),
+            &tx,
+        );
         let signature = PackedEthSignature::sign_raw(&private_key, &msg).unwrap();
 
         let mut rlp = RlpStream::new();
@@ -1431,7 +1437,8 @@ mod tests {
         tx.v = Some(U64::from(signature.v()));
         tx.r = Some(U256::from_big_endian(signature.r()));
         tx.s = Some(U256::from_big_endian(signature.s()));
-        let request = TransactionRequest::from_bytes(data.as_slice(), 270).unwrap();
+        let request =
+            TransactionRequest::from_bytes(data.as_slice(), L2ChainId::from(270)).unwrap();
         assert!(matches!(
             L2Tx::from_request(request.0, random_tx_max_size),
             Err(SerializationTransactionError::OversizedData(_, _))
diff --git a/core/lib/types/src/tx/primitives/eip712_signature/typed_structure.rs b/core/lib/types/src/tx/primitives/eip712_signature/typed_structure.rs
index 5ad48995a5c..999afbbe604 100644
--- a/core/lib/types/src/tx/primitives/eip712_signature/typed_structure.rs
+++ b/core/lib/types/src/tx/primitives/eip712_signature/typed_structure.rs
@@ -170,7 +170,7 @@ impl Eip712Domain {
         Self {
             name: Self::NAME.to_string(),
             version: Self::VERSION.to_string(),
-            chain_id: U256::from(*chain_id),
+            chain_id: U256::from(chain_id.as_u64()),
         }
     }
 }
diff --git a/core/lib/types/src/tx/primitives/packed_eth_signature.rs b/core/lib/types/src/tx/primitives/packed_eth_signature.rs
index 63f4911ea47..b249d151ef5 100644
--- a/core/lib/types/src/tx/primitives/packed_eth_signature.rs
+++ b/core/lib/types/src/tx/primitives/packed_eth_signature.rs
@@ -150,12 +150,10 @@ impl PackedEthSignature {
     pub fn v(&self) -> u8 {
         self.0.v()
     }
-    pub fn v_with_chain_id(&self, chain_id: u16) -> u16 {
-        self.0.v() as u16 + 35 + chain_id * 2
+    pub fn v_with_chain_id(&self, chain_id: u64) -> u64 {
+        self.0.v() as u64 + 35 + chain_id * 2
     }
-    pub fn unpack_v(v: u64) -> Result<(u8, Option<u16>), ParityCryptoError> {
-        use std::convert::TryInto;
-
+    pub fn unpack_v(v: u64) -> Result<(u8, Option<u64>), ParityCryptoError> {
         if v == 27 {
             return Ok((0, None));
         } else if v == 28 {
@@ -163,9 +161,6 @@ impl PackedEthSignature {
         } else if v >= 35 {
             let chain_id = (v - 35) >> 1;
             let v = v - 35 - chain_id * 2;
-            let chain_id = chain_id
-                .try_into()
-                .map_err(|_| ParityCryptoError::Custom("Invalid chain_id".to_string()))?;
             if v == 0 {
                 return Ok((0, Some(chain_id)));
             } else if v == 1 {
diff --git a/core/lib/vm/src/tests/l1_tx_execution.rs b/core/lib/vm/src/tests/l1_tx_execution.rs
index 5afe6af7918..a231d8aba0b 100644
--- a/core/lib/vm/src/tests/l1_tx_execution.rs
+++ b/core/lib/vm/src/tests/l1_tx_execution.rs
@@ -41,7 +41,7 @@ fn test_l1_tx_execution() {
         is_service: true,
         tx_number_in_block: 0,
         sender: BOOTLOADER_ADDRESS,
-        key: tx_data.tx_hash(L2ChainId(0)),
+        key: tx_data.tx_hash(L2ChainId::from(0)),
         value: u256_to_h256(U256::from(1u32)),
     }];
 
diff --git a/core/lib/vm/src/tests/require_eip712.rs b/core/lib/vm/src/tests/require_eip712.rs
index d77e4d6a33a..4c2515ae2ef 100644
--- a/core/lib/vm/src/tests/require_eip712.rs
+++ b/core/lib/vm/src/tests/require_eip712.rs
@@ -52,7 +52,7 @@ async fn test_require_eip712() {
 
     assert_eq!(vm.get_eth_balance(beneficiary.address), U256::from(0));
 
-    let chain_id: u16 = 270;
+    let chain_id: u32 = 270;
 
     // First, let's set the owners of the AA account to the private_address.
     // (so that messages signed by private_address, are authorized to act on behalf of the AA account).
@@ -94,7 +94,7 @@ async fn test_require_eip712() {
     };
 
     let aa_tx = private_account.sign_legacy_tx(aa_raw_tx).await;
-    let (tx_request, hash) = TransactionRequest::from_bytes(&aa_tx, 270).unwrap();
+    let (tx_request, hash) = TransactionRequest::from_bytes(&aa_tx, L2ChainId::from(270)).unwrap();
 
     let mut l2_tx: L2Tx = L2Tx::from_request(tx_request, 10000).unwrap();
     l2_tx.set_input(aa_tx, hash);
@@ -134,15 +134,16 @@ async fn test_require_eip712() {
 
     let transaction_request: TransactionRequest = tx_712.into();
 
-    let domain = Eip712Domain::new(L2ChainId(chain_id));
+    let domain = Eip712Domain::new(L2ChainId::from(chain_id));
     let signature = private_account
         .get_pk_signer()
         .sign_typed_data(&domain, &transaction_request)
         .await
         .unwrap();
-    let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId(chain_id));
+    let encoded_tx = transaction_request.get_signed_bytes(&signature, L2ChainId::from(chain_id));
 
-    let (aa_txn_request, aa_hash) = TransactionRequest::from_bytes(&encoded_tx, chain_id).unwrap();
+    let (aa_txn_request, aa_hash) =
+        TransactionRequest::from_bytes(&encoded_tx, L2ChainId::from(chain_id)).unwrap();
 
     let mut l2_tx = L2Tx::from_request(aa_txn_request, 100000).unwrap();
     l2_tx.set_input(encoded_tx, aa_hash);
diff --git a/core/lib/vm/src/tests/tester/vm_tester.rs b/core/lib/vm/src/tests/tester/vm_tester.rs
index 19450244120..07dbf89a8eb 100644
--- a/core/lib/vm/src/tests/tester/vm_tester.rs
+++ b/core/lib/vm/src/tests/tester/vm_tester.rs
@@ -142,7 +142,7 @@ impl<H: HistoryMode> VmTesterBuilder<H> {
                 gas_limit: BLOCK_GAS_LIMIT,
                 execution_mode: TxExecutionMode::VerifyExecute,
                 default_validation_computational_gas_limit: BLOCK_GAS_LIMIT,
-                chain_id: L2ChainId(270),
+                chain_id: L2ChainId::from(270),
             },
             deployer: None,
             rich_accounts: vec![],
diff --git a/core/lib/zksync_core/src/api_server/web3/namespaces/eth.rs b/core/lib/zksync_core/src/api_server/web3/namespaces/eth.rs
index 89434de7911..b68cfc247be 100644
--- a/core/lib/zksync_core/src/api_server/web3/namespaces/eth.rs
+++ b/core/lib/zksync_core/src/api_server/web3/namespaces/eth.rs
@@ -369,7 +369,7 @@ impl<G: L1GasPriceProvider> EthNamespace<G> {
 
     #[tracing::instrument(skip(self))]
     pub fn chain_id_impl(&self) -> U64 {
-        self.state.api_config.l2_chain_id.0.into()
+        self.state.api_config.l2_chain_id.as_u64().into()
     }
 
     #[tracing::instrument(skip(self))]
diff --git a/core/lib/zksync_core/src/api_server/web3/namespaces/net.rs b/core/lib/zksync_core/src/api_server/web3/namespaces/net.rs
index b31279ab693..88a732505ab 100644
--- a/core/lib/zksync_core/src/api_server/web3/namespaces/net.rs
+++ b/core/lib/zksync_core/src/api_server/web3/namespaces/net.rs
@@ -11,7 +11,7 @@ impl NetNamespace {
     }
 
     pub fn version_impl(&self) -> String {
-        self.zksync_network_id.to_string()
+        self.zksync_network_id.as_u64().to_string()
     }
 
     pub fn peer_count_impl(&self) -> U256 {
diff --git a/core/lib/zksync_core/src/api_server/web3/state.rs b/core/lib/zksync_core/src/api_server/web3/state.rs
index 8ea44db4a63..6ed90ec1d3c 100644
--- a/core/lib/zksync_core/src/api_server/web3/state.rs
+++ b/core/lib/zksync_core/src/api_server/web3/state.rs
@@ -65,7 +65,7 @@ impl InternalApiConfig {
     ) -> Self {
         Self {
             l1_chain_id: eth_config.network.chain_id(),
-            l2_chain_id: L2ChainId(eth_config.zksync_network_id),
+            l2_chain_id: eth_config.zksync_network_id,
             max_tx_size: web3_config.max_tx_size,
             estimate_gas_scale_factor: web3_config.estimate_gas_scale_factor,
             estimate_gas_acceptable_overestimation: web3_config
@@ -195,7 +195,7 @@ impl<E> Clone for RpcState<E> {
 impl<E> RpcState<E> {
     pub fn parse_transaction_bytes(&self, bytes: &[u8]) -> Result<(L2Tx, H256), Web3Error> {
         let chain_id = self.api_config.l2_chain_id;
-        let (tx_request, hash) = api::TransactionRequest::from_bytes(bytes, chain_id.0)?;
+        let (tx_request, hash) = api::TransactionRequest::from_bytes(bytes, chain_id)?;
 
         Ok((
             L2Tx::from_request(tx_request, self.api_config.max_tx_size)?,
diff --git a/core/lib/zksync_core/src/genesis.rs b/core/lib/zksync_core/src/genesis.rs
index f613b2b6a48..ccc9e949d2d 100644
--- a/core/lib/zksync_core/src/genesis.rs
+++ b/core/lib/zksync_core/src/genesis.rs
@@ -389,7 +389,7 @@ mod tests {
             first_l1_verifier_config: L1VerifierConfig::default(),
             first_verifier_address: Address::random(),
         };
-        ensure_genesis_state(&mut conn, L2ChainId(270), &params)
+        ensure_genesis_state(&mut conn, L2ChainId::from(270), &params)
             .await
             .unwrap();
 
@@ -403,8 +403,34 @@ mod tests {
         assert_ne!(root_hash, H256::zero());
 
         // Check that `ensure_genesis_state()` doesn't panic on repeated runs.
-        ensure_genesis_state(&mut conn, L2ChainId(270), &params)
+        ensure_genesis_state(&mut conn, L2ChainId::from(270), &params)
             .await
             .unwrap();
     }
+
+    #[db_test]
+    async fn running_genesis_with_big_chain_id(pool: ConnectionPool) {
+        let mut conn: StorageProcessor<'_> = pool.access_storage().await.unwrap();
+        conn.blocks_dal().delete_genesis().await.unwrap();
+
+        let params = GenesisParams {
+            protocol_version: ProtocolVersionId::latest(),
+            first_validator: Address::random(),
+            base_system_contracts: BaseSystemContracts::load_from_disk(),
+            system_contracts: get_system_smart_contracts(),
+            first_l1_verifier_config: L1VerifierConfig::default(),
+            first_verifier_address: Address::random(),
+        };
+        ensure_genesis_state(&mut conn, L2ChainId::max(), &params)
+            .await
+            .unwrap();
+
+        assert!(!conn.blocks_dal().is_genesis_needed().await.unwrap());
+        let metadata = conn
+            .blocks_dal()
+            .get_l1_batch_metadata(L1BatchNumber(0))
+            .await;
+        let root_hash = metadata.unwrap().unwrap().metadata.root_hash;
+        assert_ne!(root_hash, H256::zero());
+    }
 }
diff --git a/core/lib/zksync_core/src/lib.rs b/core/lib/zksync_core/src/lib.rs
index f40074d600c..028a746ced0 100644
--- a/core/lib/zksync_core/src/lib.rs
+++ b/core/lib/zksync_core/src/lib.rs
@@ -42,7 +42,7 @@ use zksync_types::{
     proofs::AggregationRound,
     protocol_version::{L1VerifierConfig, VerifierParams},
     system_contracts::get_system_smart_contracts,
-    Address, L2ChainId, PackedEthSignature, ProtocolVersionId,
+    Address, PackedEthSignature, ProtocolVersionId,
 };
 use zksync_verification_key_server::get_cached_commitments;
 
@@ -124,7 +124,7 @@ pub async fn genesis_init(
 
     genesis::ensure_genesis_state(
         &mut storage,
-        L2ChainId(network_config.zksync_network_id),
+        network_config.zksync_network_id,
         &genesis::GenesisParams {
             // We consider the operator to be the first validator for now.
             first_validator: operator_address,
@@ -365,7 +365,7 @@ pub async fn initialize_components(
         let tx_sender_config = TxSenderConfig::new(
             &state_keeper_config,
             &api_config.web3_json_rpc,
-            L2ChainId(network_config.zksync_network_id),
+            network_config.zksync_network_id,
         );
         let internal_api_config = InternalApiConfig::new(
             &network_config,
diff --git a/core/lib/zksync_core/src/metadata_calculator/helpers.rs b/core/lib/zksync_core/src/metadata_calculator/helpers.rs
index bd79b8866f4..0abcc30c644 100644
--- a/core/lib/zksync_core/src/metadata_calculator/helpers.rs
+++ b/core/lib/zksync_core/src/metadata_calculator/helpers.rs
@@ -366,7 +366,7 @@ mod tests {
     async fn loaded_logs_equivalence_basics(pool: ConnectionPool) {
         ensure_genesis_state(
             &mut pool.access_storage().await.unwrap(),
-            L2ChainId(270),
+            L2ChainId::from(270),
             &mock_genesis_params(),
         )
         .await
@@ -389,7 +389,7 @@ mod tests {
     #[db_test]
     async fn loaded_logs_equivalence_with_zero_no_op_logs(pool: ConnectionPool) {
         let mut storage = pool.access_storage().await.unwrap();
-        ensure_genesis_state(&mut storage, L2ChainId(270), &mock_genesis_params())
+        ensure_genesis_state(&mut storage, L2ChainId::from(270), &mock_genesis_params())
             .await
             .unwrap();
 
@@ -467,7 +467,7 @@ mod tests {
     #[db_test]
     async fn loaded_logs_equivalence_with_non_zero_no_op_logs(pool: ConnectionPool) {
         let mut storage = pool.access_storage().await.unwrap();
-        ensure_genesis_state(&mut storage, L2ChainId(270), &mock_genesis_params())
+        ensure_genesis_state(&mut storage, L2ChainId::from(270), &mock_genesis_params())
             .await
             .unwrap();
 
@@ -514,7 +514,7 @@ mod tests {
     #[db_test]
     async fn loaded_logs_equivalence_with_protective_reads(pool: ConnectionPool) {
         let mut storage = pool.access_storage().await.unwrap();
-        ensure_genesis_state(&mut storage, L2ChainId(270), &mock_genesis_params())
+        ensure_genesis_state(&mut storage, L2ChainId::from(270), &mock_genesis_params())
             .await
             .unwrap();
 
diff --git a/core/lib/zksync_core/src/metadata_calculator/tests.rs b/core/lib/zksync_core/src/metadata_calculator/tests.rs
index 00d34d7f870..e5e6e1f43ba 100644
--- a/core/lib/zksync_core/src/metadata_calculator/tests.rs
+++ b/core/lib/zksync_core/src/metadata_calculator/tests.rs
@@ -397,7 +397,7 @@ async fn setup_calculator_with_options(
 
     let mut storage = pool.access_storage().await.unwrap();
     if storage.blocks_dal().is_genesis_needed().await.unwrap() {
-        let chain_id = L2ChainId(270);
+        let chain_id = L2ChainId::from(270);
         let protocol_version = ProtocolVersionId::latest();
         let base_system_contracts = BaseSystemContracts::load_from_disk();
         let system_contracts = get_system_smart_contracts();
@@ -650,7 +650,7 @@ async fn deduplication_works_as_expected(pool: ConnectionPool) {
     let first_verifier_address = Address::zero();
     ensure_genesis_state(
         &mut storage,
-        L2ChainId(270),
+        L2ChainId::from(270),
         &GenesisParams {
             protocol_version,
             first_validator,
diff --git a/core/lib/zksync_core/src/state_keeper/batch_executor/tests/tester.rs b/core/lib/zksync_core/src/state_keeper/batch_executor/tests/tester.rs
index 2fd2df20e6c..d41b0c98a82 100644
--- a/core/lib/zksync_core/src/state_keeper/batch_executor/tests/tester.rs
+++ b/core/lib/zksync_core/src/state_keeper/batch_executor/tests/tester.rs
@@ -28,7 +28,7 @@ use crate::state_keeper::{
 };
 
 const DEFAULT_GAS_PER_PUBDATA: u32 = 100;
-const CHAIN_ID: L2ChainId = L2ChainId(270);
+const CHAIN_ID: u32 = 270;
 
 /// Representation of configuration parameters used by the state keeper.
 /// Has sensible defaults for most tests, each of which can be overridden.
@@ -144,7 +144,7 @@ impl Tester {
             create_genesis_l1_batch(
                 &mut storage,
                 self.fee_account,
-                CHAIN_ID,
+                L2ChainId::from(CHAIN_ID),
                 ProtocolVersionId::latest(),
                 &BASE_SYSTEM_CONTRACTS,
                 &get_system_smart_contracts(),
diff --git a/core/lib/zksync_core/src/state_keeper/io/tests/tester.rs b/core/lib/zksync_core/src/state_keeper/io/tests/tester.rs
index 5f1881afb3f..fb9ec33c54b 100644
--- a/core/lib/zksync_core/src/state_keeper/io/tests/tester.rs
+++ b/core/lib/zksync_core/src/state_keeper/io/tests/tester.rs
@@ -91,7 +91,7 @@ impl Tester {
             Duration::from_secs(1),
             l2_erc20_bridge_addr,
             BLOCK_GAS_LIMIT,
-            L2ChainId(270),
+            L2ChainId::from(270),
         )
         .await;
 
@@ -108,7 +108,7 @@ impl Tester {
             create_genesis_l1_batch(
                 &mut storage,
                 Address::repeat_byte(0x01),
-                L2ChainId(270),
+                L2ChainId::from(270),
                 ProtocolVersionId::latest(),
                 &self.base_system_contracts,
                 &get_system_smart_contracts(),
diff --git a/core/lib/zksync_core/src/state_keeper/mod.rs b/core/lib/zksync_core/src/state_keeper/mod.rs
index 5ccae06a3f4..8eef5d6adbc 100644
--- a/core/lib/zksync_core/src/state_keeper/mod.rs
+++ b/core/lib/zksync_core/src/state_keeper/mod.rs
@@ -8,7 +8,6 @@ use zksync_config::{
     ContractsConfig, DBConfig,
 };
 use zksync_dal::ConnectionPool;
-use zksync_types::L2ChainId;
 
 mod batch_executor;
 pub(crate) mod extractors;
@@ -71,7 +70,7 @@ where
         mempool_config.delay_interval(),
         contracts_config.l2_erc20_bridge_addr,
         state_keeper_config.validation_computational_gas_limit,
-        L2ChainId(network_config.zksync_network_id),
+        network_config.zksync_network_id,
     )
     .await;
 
diff --git a/core/lib/zksync_core/src/state_keeper/tests/mod.rs b/core/lib/zksync_core/src/state_keeper/tests/mod.rs
index 4f8f1fe364d..d269b1fea67 100644
--- a/core/lib/zksync_core/src/state_keeper/tests/mod.rs
+++ b/core/lib/zksync_core/src/state_keeper/tests/mod.rs
@@ -58,7 +58,7 @@ pub(super) fn default_system_env() -> SystemEnv {
         gas_limit: BLOCK_GAS_LIMIT,
         execution_mode: TxExecutionMode::VerifyExecute,
         default_validation_computational_gas_limit: BLOCK_GAS_LIMIT,
-        chain_id: L2ChainId(270),
+        chain_id: L2ChainId::from(270),
     }
 }
 
@@ -147,7 +147,7 @@ pub(super) fn create_l2_transaction(fee_per_gas: u64, gas_per_pubdata: u32) -> L
         Nonce(0),
         fee,
         U256::zero(),
-        L2ChainId(271),
+        L2ChainId::from(271),
         &H256::repeat_byte(0x11),
         None,
         PaymasterParams::default(),
diff --git a/core/lib/zksync_core/src/state_keeper/tests/tester.rs b/core/lib/zksync_core/src/state_keeper/tests/tester.rs
index b855ce54560..62bd4307b4e 100644
--- a/core/lib/zksync_core/src/state_keeper/tests/tester.rs
+++ b/core/lib/zksync_core/src/state_keeper/tests/tester.rs
@@ -286,7 +286,7 @@ pub(crate) fn pending_batch_data(
             gas_limit: BLOCK_GAS_LIMIT,
             execution_mode: TxExecutionMode::VerifyExecute,
             default_validation_computational_gas_limit: BLOCK_GAS_LIMIT,
-            chain_id: L2ChainId(270),
+            chain_id: L2ChainId::from(270),
         },
         pending_miniblocks,
     }
@@ -601,7 +601,7 @@ impl StateKeeperIO for TestIO {
                 gas_limit: BLOCK_GAS_LIMIT,
                 execution_mode: TxExecutionMode::VerifyExecute,
                 default_validation_computational_gas_limit: BLOCK_GAS_LIMIT,
-                chain_id: L2ChainId(270),
+                chain_id: L2ChainId::from(270),
             },
             L1BatchEnv {
                 previous_batch_hash: Some(H256::zero()),
diff --git a/core/multivm_deps/vm_1_3_2/src/test_utils.rs b/core/multivm_deps/vm_1_3_2/src/test_utils.rs
index 2ebaebb4e37..5acefe94a4b 100644
--- a/core/multivm_deps/vm_1_3_2/src/test_utils.rs
+++ b/core/multivm_deps/vm_1_3_2/src/test_utils.rs
@@ -172,7 +172,7 @@ pub fn mock_loadnext_test_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -209,7 +209,7 @@ pub fn mock_loadnext_gas_burn_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -276,7 +276,7 @@ pub fn get_deploy_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
@@ -303,7 +303,7 @@ pub fn get_error_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
diff --git a/core/multivm_deps/vm_m5/src/test_utils.rs b/core/multivm_deps/vm_m5/src/test_utils.rs
index 13cb91a5782..83ef7575805 100644
--- a/core/multivm_deps/vm_m5/src/test_utils.rs
+++ b/core/multivm_deps/vm_m5/src/test_utils.rs
@@ -171,7 +171,7 @@ pub fn mock_loadnext_test_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -208,7 +208,7 @@ pub fn mock_loadnext_gas_burn_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -275,7 +275,7 @@ pub fn get_deploy_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
@@ -302,7 +302,7 @@ pub fn get_error_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
diff --git a/core/multivm_deps/vm_m6/src/test_utils.rs b/core/multivm_deps/vm_m6/src/test_utils.rs
index b196ed9e357..7d7b98685ef 100644
--- a/core/multivm_deps/vm_m6/src/test_utils.rs
+++ b/core/multivm_deps/vm_m6/src/test_utils.rs
@@ -171,7 +171,7 @@ pub fn mock_loadnext_test_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -208,7 +208,7 @@ pub fn mock_loadnext_gas_burn_call(
         nonce,
         fee,
         Default::default(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &eth_private_key,
         None,
         Default::default(),
@@ -275,7 +275,7 @@ pub fn get_deploy_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
@@ -302,7 +302,7 @@ pub fn get_error_tx(
         nonce,
         fee,
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &account_private_key,
         Some(factory_deps),
         Default::default(),
diff --git a/core/tests/loadnext/src/account_pool.rs b/core/tests/loadnext/src/account_pool.rs
index c19765d2bb3..556bee7f402 100644
--- a/core/tests/loadnext/src/account_pool.rs
+++ b/core/tests/loadnext/src/account_pool.rs
@@ -1,4 +1,4 @@
-use std::{collections::VecDeque, str::FromStr, sync::Arc, time::Duration};
+use std::{collections::VecDeque, convert::TryFrom, str::FromStr, sync::Arc, time::Duration};
 
 use once_cell::sync::OnceCell;
 use rand::Rng;
@@ -90,7 +90,7 @@ pub struct AccountPool {
 impl AccountPool {
     /// Generates all the required test accounts and prepares `Wallet` objects.
     pub async fn new(config: &LoadtestConfig) -> anyhow::Result<Self> {
-        let l2_chain_id = L2ChainId(config.l2_chain_id);
+        let l2_chain_id = L2ChainId::try_from(config.l2_chain_id).unwrap();
         // Create a client for pinging the rpc.
         let client = HttpClientBuilder::default()
             .build(&config.l2_rpc_address)
diff --git a/core/tests/loadnext/src/config.rs b/core/tests/loadnext/src/config.rs
index 1c4b5ae7733..d62f4cdb63e 100644
--- a/core/tests/loadnext/src/config.rs
+++ b/core/tests/loadnext/src/config.rs
@@ -103,7 +103,7 @@ pub struct LoadtestConfig {
 
     /// Chain id of L2 node.
     #[serde(default = "default_l2_chain_id")]
-    pub l2_chain_id: u16,
+    pub l2_chain_id: u64,
 
     /// RPC address of L2 node.
     #[serde(default = "default_l2_rpc_address")]
@@ -227,9 +227,9 @@ fn default_seed() -> Option<String> {
     result
 }
 
-fn default_l2_chain_id() -> u16 {
+fn default_l2_chain_id() -> u64 {
     // 270 for rinkeby
-    let result = *L2ChainId::default();
+    let result = L2ChainId::default().as_u64();
     tracing::info!("Using default L2_CHAIN_ID: {result}");
     result
 }
diff --git a/core/tests/vm-benchmark/harness/src/lib.rs b/core/tests/vm-benchmark/harness/src/lib.rs
index 55b4eb238d7..e439e1359fb 100644
--- a/core/tests/vm-benchmark/harness/src/lib.rs
+++ b/core/tests/vm-benchmark/harness/src/lib.rs
@@ -84,7 +84,7 @@ impl BenchmarkingVm {
                 gas_limit: BLOCK_GAS_LIMIT,
                 execution_mode: TxExecutionMode::VerifyExecute,
                 default_validation_computational_gas_limit: BLOCK_GAS_LIMIT,
-                chain_id: L2ChainId(270),
+                chain_id: L2ChainId::from(270),
             },
             Rc::new(RefCell::new(StorageView::new(&*STORAGE))),
             HistoryEnabled,
@@ -120,7 +120,7 @@ pub fn get_deploy_tx(code: &[u8]) -> Transaction {
             gas_per_pubdata_limit: U256::from(MAX_GAS_PER_PUBDATA_BYTE),
         },
         U256::zero(),
-        L2ChainId(270),
+        L2ChainId::from(270),
         &PRIVATE_KEY,
         Some(vec![code.to_vec()]), // maybe not needed?
         Default::default(),