diff --git a/lib/irc/command.ex b/lib/irc/command.ex
index 12725b8..b0350db 100644
--- a/lib/irc/command.ex
+++ b/lib/irc/command.ex
@@ -1,5 +1,5 @@
 ##
-# Copyright (C) 2021-2022  Valentin Lorentz
+# Copyright (C) 2021-2023  Valentin Lorentz
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License version 3,
@@ -251,6 +251,8 @@ defmodule M51.Irc.Command do
 
   """
   def downgrade(command, capabilities) do
+    original_tags = command.tags
+
     # downgrade echo-message
     command =
       if Enum.member?(capabilities, :echo_message) do
@@ -319,6 +321,47 @@ defmodule M51.Irc.Command do
             nil
           end
 
+        %{command: "REDACT"} ->
+          if Enum.member?(capabilities, :message_redaction) do
+            command
+          else
+            sender = Map.get(original_tags, "account")
+
+            display_name =
+              case Map.get(original_tags, "+draft/display-name", nil) do
+                dn when is_binary(dn) -> " (#{dn})"
+                _ -> ""
+              end
+
+            tags = Map.drop(command.tags, ["+draft/display-name", "account"])
+
+            command =
+              case command do
+                %{params: [channel, msgid, reason]} ->
+                  %M51.Irc.Command{
+                    tags: Map.put(tags, "+draft/reply", msgid),
+                    source: "server.",
+                    command: "NOTICE",
+                    params: [channel, "#{sender}#{display_name} deleted an event: #{reason}"]
+                  }
+
+                %{params: [channel, msgid]} ->
+                  %M51.Irc.Command{
+                    tags: Map.put(tags, "+draft/reply", msgid),
+                    source: "server.",
+                    command: "NOTICE",
+                    params: [channel, "#{sender}#{display_name} deleted an event"]
+                  }
+
+                _ ->
+                  # shouldn't happen
+                  nil
+              end
+
+            # run downgrade() recursively in order to drop the new tags if necessary
+            downgrade(command, capabilities)
+          end
+
         %{command: "TAGMSG"} ->
           if Enum.member?(capabilities, :message_tags) do
             command
diff --git a/lib/irc/handler.ex b/lib/irc/handler.ex
index 8398eb3..8e6bf03 100644
--- a/lib/irc/handler.ex
+++ b/lib/irc/handler.ex
@@ -72,6 +72,9 @@ defmodule M51.IrcConn.Handler do
     # https://ircv3.net/specs/extensions/multiline
     "draft/multiline" => {:multiline, "max-bytes=#{@multiline_max_bytes}"},
 
+    # https://github.com/progval/ircv3-specifications/blob/redaction/extensions/message-redaction.md
+    "draft/message-redaction" => {:message_redaction, nil},
+
     # https://ircv3.net/specs/extensions/sasl-3.1
     "sasl" => {:sasl, "PLAIN"},
 
@@ -903,6 +906,27 @@ defmodule M51.IrcConn.Handler do
       {"TAGMSG", _} ->
         send_needmoreparams.()
 
+      {"REDACT", [channel, targetmsgid, reason | _]} ->
+        send_redact(
+          sup_pid,
+          channel,
+          Map.get(command.tags, "label"),
+          targetmsgid,
+          reason
+        )
+
+      {"REDACT", [channel, targetmsgid | _]} ->
+        send_redact(
+          sup_pid,
+          channel,
+          Map.get(command.tags, "label"),
+          targetmsgid,
+          nil
+        )
+
+      {"REDACT", _} ->
+        send_needmoreparams.()
+
       {"CHATHISTORY", ["TARGETS", _ts1, _ts2, _limit | _]} ->
         # This is mainly used for PMs, and we don't support those yet; so there
         # is little point in storing state to actually implement it
@@ -1374,6 +1398,61 @@ defmodule M51.IrcConn.Handler do
     end
   end
 
+  defp send_redact(sup_pid, channel, label, targetmsgid, reason) do
+    writer = M51.IrcConn.Supervisor.writer(sup_pid)
+    matrix_client = M51.IrcConn.Supervisor.matrix_client(sup_pid)
+    matrix_state = M51.IrcConn.Supervisor.matrix_state(sup_pid)
+    send = fn cmd -> M51.IrcConn.Writer.write_command(writer, cmd) end
+
+    # If the client provided a label, use it as txnId on Matrix's side.
+    # This way we can parse it when receiving the echo from Matrix's event
+    # stream instead of storing state.
+    # Otherwise, generate a random transaction id.
+
+    nicklist =
+      case M51.MatrixClient.State.room_from_irc_channel(matrix_state, channel) do
+        {_room_id, room} -> room.members |> Map.keys()
+        nil -> []
+      end
+
+    reason =
+      case reason do
+        nil ->
+          nil
+
+        reason ->
+          {reason, _formatted_reason} = M51.Format.irc2matrix(reason, nicklist)
+          reason
+      end
+
+    result =
+      M51.MatrixClient.Client.send_redact(
+        matrix_client,
+        channel,
+        label,
+        targetmsgid,
+        reason
+      )
+
+    case result do
+      {:ok, _event_id} ->
+        nil
+
+      {:error, error} ->
+        send.(%M51.Irc.Command{
+          source: "server.",
+          command: "FAIL",
+          params: [
+            "REDACT",
+            "UNKNOWN_ERROR",
+            channel,
+            targetmsgid,
+            "Error while redacting message: " <> Kernel.inspect(error)
+          ]
+        })
+    end
+  end
+
   defp close_connection(sup_pid) do
     writer = M51.IrcConn.Supervisor.writer(sup_pid)
     M51.IrcConn.Writer.close(writer)
diff --git a/lib/matrix_client/client.ex b/lib/matrix_client/client.ex
index ff35fe7..6b78566 100644
--- a/lib/matrix_client/client.ex
+++ b/lib/matrix_client/client.ex
@@ -296,6 +296,42 @@ defmodule M51.MatrixClient.Client do
     end
   end
 
+  @impl true
+  def handle_call({:send_redact, channel, label, event_id, reason}, _from, state) do
+    %M51.MatrixClient.Client{
+      state: :connected,
+      irc_pid: irc_pid,
+      raw_client: raw_client
+    } = state
+
+    matrix_state = M51.IrcConn.Supervisor.matrix_state(irc_pid)
+
+    transaction_id = label_to_transaction_id(label)
+
+    reply =
+      case M51.MatrixClient.State.room_from_irc_channel(matrix_state, channel) do
+        nil ->
+          {:reply, {:error, {:room_not_found, channel}}, state}
+
+        {room_id, _room} ->
+          path =
+            "/_matrix/client/r0/rooms/#{urlquote(room_id)}/redact/#{urlquote(event_id)}/#{transaction_id}"
+
+          body =
+            case reason do
+              reason when is_binary(reason) -> Jason.encode!(%{"reason" => reason})
+              _ -> Jason.encode!({})
+            end
+
+          case M51.Matrix.RawClient.put(raw_client, path, body) do
+            {:ok, %{"event_id" => event_id}} -> {:ok, event_id}
+            {:error, error} -> {:error, error}
+          end
+      end
+
+    {:reply, reply, state}
+  end
+
   @impl true
   def handle_call({:get_event_context, channel, event_id, limit}, _from, state) do
     %M51.MatrixClient.Client{
@@ -543,13 +579,23 @@ defmodule M51.MatrixClient.Client do
   @doc """
     Sends the given event object.
 
-    If 'label' is not nil, it will be passed as a 'label' message tagt when
+    If 'label' is not nil, it will be passed as a 'label' message tag when
     the event is seen in the event stream.
   """
   def send_event(pid, channel, label, event_type, event) do
     GenServer.call(pid, {:send_event, channel, event_type, label, event}, @timeout)
   end
 
+  @doc """
+    Asks the server to redact the event with the given id
+
+    If 'label' is not nil, it will be passed as a 'label' message tag when
+    the event is seen in the event stream.
+  """
+  def send_redact(pid, channel, label, event_id, reason) do
+    GenServer.call(pid, {:send_redact, channel, label, event_id, reason}, @timeout)
+  end
+
   @doc """
     Returns events that happened just before or after the specified event_id.
 
diff --git a/lib/matrix_client/poller.ex b/lib/matrix_client/poller.ex
index 9864a7b..07d4c24 100644
--- a/lib/matrix_client/poller.ex
+++ b/lib/matrix_client/poller.ex
@@ -1,5 +1,5 @@
 ##
-# Copyright (C) 2021-2022  Valentin Lorentz
+# Copyright (C) 2021-2023  Valentin Lorentz
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License version 3,
@@ -884,38 +884,41 @@ defmodule M51.MatrixClient.Poller do
     member = M51.MatrixClient.State.room_member(state, room_id, sender)
     send = make_send_function(sup_pid, event, write)
 
-    reason =
-      case event["content"] do
-        %{"reason" => reason} when is_binary(reason) -> ": #{reason}"
-        _ -> ""
-      end
+    tags = %{"account" => sender}
 
     # TODO: dedup this with m.reaction handler
-    display_name =
+    tags =
       case member do
         %M51.Matrix.RoomMember{display_name: display_name} when display_name != nil ->
-          " (#{display_name})"
+          Map.put(tags, "+draft/display-name", display_name)
 
         _ ->
-          ""
+          tags
       end
 
-    tags =
-      case event do
-        %{"redacts" => redacts_id}
-        when is_binary(redacts_id) ->
-          %{"+draft/reply" => redacts_id}
+    case event do
+      %{"redacts" => redacts_id} when is_binary(redacts_id) ->
+        case event["content"] do
+          %{"reason" => reason} when is_binary(reason) ->
+            send.(%M51.Irc.Command{
+              tags: tags,
+              source: nick2nuh(sender),
+              command: "REDACT",
+              params: [channel, redacts_id, reason]
+            })
 
-        _ ->
-          %{}
-      end
+          _ ->
+            send.(%M51.Irc.Command{
+              tags: tags,
+              source: nick2nuh(sender),
+              command: "REDACT",
+              params: [channel, redacts_id]
+            })
+        end
 
-    send.(%M51.Irc.Command{
-      tags: tags,
-      source: "server.",
-      command: "NOTICE",
-      params: [channel, "#{sender}#{display_name} deleted an event#{reason}"]
-    })
+      _ ->
+        nil
+    end
   end
 
   def handle_event(
diff --git a/test/irc/handler_test.exs b/test/irc/handler_test.exs
index a413726..e8f5091 100644
--- a/test/irc/handler_test.exs
+++ b/test/irc/handler_test.exs
@@ -18,8 +18,8 @@ defmodule M51.IrcConn.HandlerTest do
   use ExUnit.Case, async: false
   doctest M51.IrcConn.Handler
 
-  @cap_ls_302 ":server. CAP * LS :account-tag batch draft/account-registration=before-connect draft/channel-rename draft/chathistory draft/multiline=max-bytes=8192 draft/sasl-ir echo-message extended-join labeled-response message-tags sasl=PLAIN server-time soju.im/account-required standard-replies userhost-in-names\r\n"
-  @cap_ls ":server. CAP * LS :account-tag batch draft/account-registration draft/channel-rename draft/chathistory draft/multiline draft/sasl-ir echo-message extended-join labeled-response message-tags sasl server-time soju.im/account-required standard-replies userhost-in-names\r\n"
+  @cap_ls_302 ":server. CAP * LS :account-tag batch draft/account-registration=before-connect draft/channel-rename draft/chathistory draft/message-redaction draft/multiline=max-bytes=8192 draft/sasl-ir echo-message extended-join labeled-response message-tags sasl=PLAIN server-time soju.im/account-required standard-replies userhost-in-names\r\n"
+  @cap_ls ":server. CAP * LS :account-tag batch draft/account-registration draft/channel-rename draft/chathistory draft/message-redaction draft/multiline draft/sasl-ir echo-message extended-join labeled-response message-tags sasl server-time soju.im/account-required standard-replies userhost-in-names\r\n"
   @isupport "CASEMAPPING=rfc3454 CLIENTTAGDENY=*,-draft/react,-draft/reply CHANLIMIT= CHANTYPES=#! CHATHISTORY=100 MAXTARGETS=1 MSGREFTYPES=msgid PREFIX= TARGMAX=JOIN:1,PART:1 UTF8ONLY :are supported by this server\r\n"
 
   setup do
@@ -1078,4 +1078,20 @@ defmodule M51.IrcConn.HandlerTest do
 
     assert_line("BATCH :-#{batch_id}\r\n")
   end
+
+  test "redact a message for no reason", %{handler: handler} do
+    do_connection_registration(handler)
+
+    send(handler, cmd("REDACT #existing_room:example.org $event1"))
+
+    assert_message({:send_redact, "#existing_room:example.org", nil, "$event1", nil})
+  end
+
+  test "redact a message for a reason", %{handler: handler} do
+    do_connection_registration(handler)
+
+    send(handler, cmd("REDACT #existing_room:example.org $event1 :spam"))
+
+    assert_message({:send_redact, "#existing_room:example.org", nil, "$event1", "spam"})
+  end
 end
diff --git a/test/matrix_client/poller_test.exs b/test/matrix_client/poller_test.exs
index facc10e..3885fca 100644
--- a/test/matrix_client/poller_test.exs
+++ b/test/matrix_client/poller_test.exs
@@ -1,5 +1,5 @@
 ##
-# Copyright (C) 2021-2022  Valentin Lorentz
+# Copyright (C) 2021-2023  Valentin Lorentz
 #
 # This program is free software: you can redistribute it and/or modify
 # it under the terms of the GNU Affero General Public License version 3,
@@ -2288,7 +2288,7 @@ defmodule M51.MatrixClient.PollerTest do
     })
 
     assert_line(":nick:example.org!nick@example.org PRIVMSG #test:example.org :first message\r\n")
-    # m.room.redaction not implemented yet, so it's just ignored
+    # We'll probably see the m.room.redaction message later, so we can simply ignore this one.
     assert_line(
       ":nick:example.org!nick@example.org PRIVMSG #test:example.org :second message\r\n"
     )
@@ -2297,6 +2297,71 @@ defmodule M51.MatrixClient.PollerTest do
   end
 
   test "message redaction" do
+    M51.IrcConn.State.add_capabilities(:process_ircconn_state, [
+      :multiline,
+      :message_tags,
+      :message_redaction
+    ])
+
+    joined_room()
+
+    timeline_events = [
+      %{
+        "content" => %{"body" => "first message", "msgtype" => "m.text"},
+        "event_id" => "$event1",
+        "origin_server_ts" => 1_632_946_233_579,
+        "sender" => "@nick:example.org",
+        "type" => "m.room.message",
+        "unsigned" => %{}
+      },
+      %{
+        "content" => %{},
+        "event_id" => "$event2",
+        "redacts" => "$event1",
+        "origin_server_ts" => 1_633_808_172_505,
+        "sender" => "@admin:example.org",
+        "type" => "m.room.redaction",
+        "unsigned" => %{}
+      },
+      %{
+        "content" => %{
+          "reason" => "Redacting again!"
+        },
+        "event_id" => "$event3",
+        "redacts" => "$event1",
+        "origin_server_ts" => 1_633_808_172_505,
+        "sender" => "@admin:example.org",
+        "type" => "m.room.redaction",
+        "unsigned" => %{}
+      }
+    ]
+
+    M51.MatrixClient.Poller.handle_events(self(), false, %{
+      "rooms" => %{
+        "join" => %{
+          "!testid:example.org" => %{
+            "timeline" => %{"events" => timeline_events}
+          }
+        }
+      }
+    })
+
+    assert_line(
+      "@msgid=$event1 :nick:example.org!nick@example.org PRIVMSG #test:example.org :first message\r\n"
+    )
+
+    assert_line(
+      "@msgid=$event2 :admin:example.org!admin@example.org REDACT #test:example.org :$event1\r\n"
+    )
+
+    assert_line(
+      "@msgid=$event3 :admin:example.org!admin@example.org REDACT #test:example.org $event1 :Redacting again!\r\n"
+    )
+
+    assert_last_line()
+  end
+
+  test "message redaction fallback" do
     M51.IrcConn.State.add_capabilities(:process_ircconn_state, [
       :multiline,
       :message_tags