diff --git a/include/podio/AssociationCollection.h b/include/podio/AssociationCollection.h
index e7d577c5d..ba4dfb276 100644
--- a/include/podio/AssociationCollection.h
+++ b/include/podio/AssociationCollection.h
@@ -133,7 +133,7 @@ class AssociationCollection : public podio::CollectionBase {
   }
 
   std::string getValueTypeName() const override {
-    return std::string("podio::Association<") + FromT::TypeName + "," + ToT::TypeName + ">";
+    return podio::detail::associationSIOName<FromT, ToT>();
   }
 
   std::string getDataTypeName() const override {
diff --git a/include/podio/AssociationFwd.h b/include/podio/AssociationFwd.h
index 3e36dfc90..ed2524a35 100644
--- a/include/podio/AssociationFwd.h
+++ b/include/podio/AssociationFwd.h
@@ -1,7 +1,9 @@
 #ifndef PODIO_ASSOCIATIONFWD_H
 #define PODIO_ASSOCIATIONFWD_H
 
+#include <algorithm>
 #include <deque>
+#include <string>
 #include <vector>
 
 namespace podio {
@@ -22,6 +24,10 @@ namespace detail {
   template <typename T>
   using GetDefT = typename GetDefType<T>::type;
 
+  /**
+   * Helper template struct and type-alias to retrieve the collection type from
+   * a given data type
+   */
   template <typename T>
   struct GetCollType {
     using type = typename T::CollT;
@@ -30,6 +36,12 @@ namespace detail {
   template <typename T>
   using GetCollT = typename GetCollType<T>::type;
 
+  template <typename FromT, typename ToT>
+  inline std::string associationSIOName() {
+    auto n = std::string("Association_FROM_") + FromT::TypeName + "_TO_" + FromT::TypeName;
+    std::replace(n.begin(), n.end(), ':', '_');
+    return n;
+  }
 } // namespace detail
 
 // Forward declarations and typedefs used throughout the whole Association
diff --git a/include/podio/AssociationSIOBlock.h b/include/podio/AssociationSIOBlock.h
new file mode 100644
index 000000000..00683b803
--- /dev/null
+++ b/include/podio/AssociationSIOBlock.h
@@ -0,0 +1,78 @@
+#ifndef PODIO_ASSOCIATIONSIOBLOCK_H
+#define PODIO_ASSOCIATIONSIOBLOCK_H
+
+#include "podio/AssociationFwd.h"
+#include "podio/SIOBlock.h"
+
+#include <sio/api.h>
+#include <sio/io_device.h>
+#include <sio/version.h>
+
+#include <algorithm>
+#include <string>
+
+namespace podio {
+template <typename FromT, typename ToT>
+class AssociationSIOBlock : public podio::SIOBlock {
+public:
+  AssociationSIOBlock() :
+      SIOBlock(podio::detail::associationSIOName<FromT, ToT>(), sio::version::encode_version(0, 1)) {
+    podio::SIOBlockFactory::instance().registerBlockForCollection(podio::detail::associationSIOName<FromT, ToT>(),
+                                                                  this);
+  }
+
+  AssociationSIOBlock(const std::string& name) : SIOBlock(name, sio::version::encode_version(0, 1)) {
+  }
+
+  void read(sio::read_device& device, sio::version_type) override {
+    auto buffers = _col->getBuffers();
+    if (!_col->isSubsetCollection()) {
+      auto* dataVec = buffers.dataAsVector<float>();
+      unsigned size{0};
+      device.data(size);
+      dataVec->resize(size);
+      podio::handlePODDataSIO(device, dataVec->data(), size);
+    }
+
+    // ---- references
+    auto* refColls = buffers.references;
+    for (auto& refC : *refColls) {
+      unsigned size{0};
+      device.data(size);
+      refC->resize(size);
+      podio::handlePODDataSIO(device, refC->data(), size);
+    }
+  }
+
+  void write(sio::write_device& device) override {
+    _col->prepareForWrite();
+    auto buffers = _col->getBuffers();
+    if (!_col->isSubsetCollection()) {
+      auto* dataVec = buffers.dataAsVector<float>();
+      unsigned size = dataVec->size();
+      device.data(size);
+      podio::handlePODDataSIO(device, dataVec->data(), size);
+    }
+
+    // ---- references
+    auto* refColls = buffers.references;
+    for (auto& refC : *refColls) {
+      unsigned size = refC->size();
+      device.data(size);
+      podio::handlePODDataSIO(device, refC->data(), size);
+    }
+  }
+
+  void createCollection(const bool subsetCollection = false) override {
+    setCollection(new AssociationCollection<FromT, ToT>());
+    _col->setSubsetCollection(subsetCollection);
+  }
+
+  SIOBlock* create(const std::string& name) const override {
+    return new AssociationSIOBlock(name);
+  }
+};
+
+} // namespace podio
+
+#endif // PODIO_ASSOCIATIONBLOCK_H
diff --git a/tests/associations.cpp b/tests/associations.cpp
index b479796b8..23c5a6876 100644
--- a/tests/associations.cpp
+++ b/tests/associations.cpp
@@ -133,9 +133,7 @@ TEST_CASE("Association basics", "[associations]") {
 TEST_CASE("AssociationCollection basics", "[associations]") {
   auto coll = TestAColl();
 
-  REQUIRE(coll.getValueTypeName() == "podio::Association<ExampleHit,ExampleCluster>");
-
-  REQUIRE(true);
+  // TODO: basics without I/O
 }
 
 TEST_CASE("AssociationCollection constness", "[associations][static-checks][const-correctness]") {
diff --git a/tests/read_and_write_sio.cpp b/tests/read_and_write_sio.cpp
index 69f25d270..513fea823 100644
--- a/tests/read_and_write_sio.cpp
+++ b/tests/read_and_write_sio.cpp
@@ -1,9 +1,13 @@
 #include "read_test.h"
 
+#include "podio/AssociationSIOBlock.h"
 #include "podio/EventStore.h"
 #include "podio/SIOReader.h"
 #include "podio/SIOWriter.h"
 
+// User needs to declare this for generation and plugin loading for SIO!
+static podio::AssociationSIOBlock<ExampleMC, ex42::ExampleWithARelation> anAssoc;
+
 int main() {
   podio::SIOReader reader;
   reader.openFile("example.sio");
diff --git a/tests/read_sio.cpp b/tests/read_sio.cpp
index a45830eed..837136832 100644
--- a/tests/read_sio.cpp
+++ b/tests/read_sio.cpp
@@ -1,6 +1,13 @@
+#include "podio/AssociationSIOBlock.h"
 #include "podio/SIOReader.h"
 #include "read_test.h"
 
+#include "datamodel/ExampleMC.h"
+#include "datamodel/ExampleWithARelation.h"
+
+// User needs to declare this for generation and plugin loading for SIO!
+static podio::AssociationSIOBlock<ExampleMC, ex42::ExampleWithARelation> anAssoc;
+
 int main() {
   //  auto reader = podio::SIOReader();
   podio::SIOReader reader; // SIOReader has no copy c'tor ...
diff --git a/tests/read_test.h b/tests/read_test.h
index 7e67600ad..876317adb 100644
--- a/tests/read_test.h
+++ b/tests/read_test.h
@@ -395,10 +395,11 @@ void processEvent(podio::EventStore& store, int eventNum, podio::version::Versio
   if (associations.size() != nmspaces.size()) {
     throw std::runtime_error("AssociationsCollection does not have the expected size");
   }
+  const auto nNameSpc = nmspaces.size();
   int assocIndex = 0;
   for (auto assoc : associations) {
     if (!((assoc.getWeight() == 0.5 * assocIndex) && (assoc.getFrom() == mcps[assocIndex]) &&
-          (assoc.getTo() == nmspaces[assocIndex]))) {
+          (assoc.getTo() == nmspaces[nNameSpc - 1 - assocIndex]))) {
       throw std::runtime_error("Association does not have expected content");
     }
     assocIndex++;
diff --git a/tests/read_timed_sio.cpp b/tests/read_timed_sio.cpp
index c109f0bee..9d282a484 100644
--- a/tests/read_timed_sio.cpp
+++ b/tests/read_timed_sio.cpp
@@ -1,8 +1,16 @@
+#include "podio/AssociationSIOBlock.h"
 #include "podio/BenchmarkRecorder.h"
 #include "podio/SIOReader.h"
 #include "podio/TimedReader.h"
+
+#include "datamodel/ExampleMC.h"
+#include "datamodel/ExampleWithARelation.h"
+
 #include "read_test.h"
 
+// User needs to declare this for generation and plugin loading for SIO!
+static podio::AssociationSIOBlock<ExampleMC, ex42::ExampleWithARelation> anAssoc;
+
 int main() {
   podio::benchmark::BenchmarkRecorder recorder("read_benchmark_sio.root");
 
diff --git a/tests/write_sio.cpp b/tests/write_sio.cpp
index 9068f312c..743fd6fe0 100644
--- a/tests/write_sio.cpp
+++ b/tests/write_sio.cpp
@@ -1,7 +1,15 @@
+#include "podio/AssociationSIOBlock.h"
 #include "podio/EventStore.h"
 #include "podio/SIOWriter.h"
+
+#include "datamodel/ExampleMC.h"
+#include "datamodel/ExampleWithARelation.h"
+
 #include "write_test.h"
 
+// User needs to declare this for generation and plugin loading for SIO!
+static podio::AssociationSIOBlock<ExampleMC, ex42::ExampleWithARelation> anAssoc;
+
 int main(int, char**) {
   podio::EventStore store;
   podio::SIOWriter writer("example.sio", &store);
diff --git a/tests/write_timed_sio.cpp b/tests/write_timed_sio.cpp
index 6edb8b771..3f35764ab 100644
--- a/tests/write_timed_sio.cpp
+++ b/tests/write_timed_sio.cpp
@@ -1,8 +1,15 @@
+#include "podio/AssociationSIOBlock.h"
 #include "podio/BenchmarkRecorder.h"
 #include "podio/EventStore.h"
 #include "podio/SIOWriter.h"
 #include "podio/TimedWriter.h"
+
+#include "datamodel/ExampleMC.h"
+#include "datamodel/ExampleWithARelation.h"
+
 #include "write_test.h"
+// User needs to declare this for generation and plugin loading for SIO!
+static podio::AssociationSIOBlock<ExampleMC, ex42::ExampleWithARelation> anAssoc;
 
 int main() {
   podio::benchmark::BenchmarkRecorder recorder("write_benchmark_sio.root");