diff --git a/core/src/main/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidator.java b/core/src/main/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidator.java
index 01638b4..761b760 100644
--- a/core/src/main/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidator.java
+++ b/core/src/main/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidator.java
@@ -2,6 +2,7 @@
 
 
 import lombok.RequiredArgsConstructor;
+import org.lfenergy.shapeshifter.api.FlexRequest;
 import org.lfenergy.shapeshifter.api.PayloadMessageResponseType;
 import org.lfenergy.shapeshifter.api.PayloadMessageType;
 import org.lfenergy.shapeshifter.core.model.UftpMessage;
@@ -13,27 +14,27 @@
 @RequiredArgsConstructor
 public class ReferencedRequestMessageIdInResponseValidator implements UftpValidator<PayloadMessageResponseType> {
 
-  private final UftpMessageSupport support;
-
-  @Override
-  public boolean appliesTo(Class<? extends PayloadMessageType> clazz) {
-    return UftpRequestResponseMapping.hasReferencedRequestMessageId(clazz);
-  }
-
-  @Override
-  public int order() {
-    return 0;
-  }
-
-  @Override
-  public boolean isValid(UftpMessage<PayloadMessageResponseType> message) {
-    var value = UftpRequestResponseMapping.getReferencedRequestMessageId(message.payloadMessage());
-    return value.isEmpty() || support.findDuplicateMessage(value.get(), message.payloadMessage().getSenderDomain() ,
-            message.payloadMessage().getRecipientDomain()).isPresent();
-  }
-
-  @Override
-  public String getReason() {
-    return "Unknown reference Request message ID";
-  }
+    private final UftpMessageSupport support;
+
+    @Override
+    public boolean appliesTo(Class<? extends PayloadMessageType> clazz) {
+        return UftpRequestResponseMapping.hasReferencedRequestMessageId(clazz);
+    }
+
+    @Override
+    public int order() {
+        return 0;
+    }
+
+    @Override
+    public boolean isValid(UftpMessage<PayloadMessageResponseType> message) {
+        var value = UftpRequestResponseMapping.getReferencedRequestMessageId(message.payloadMessage());
+        return value.isPresent() && support.findReferencedMessage(message.referenceToPreviousMessage(value.get(), message.payloadMessage().getConversationID(),
+                FlexRequest.class)).isPresent();
+    }
+
+    @Override
+    public String getReason() {
+        return "Unknown reference Request message ID";
+    }
 }
diff --git a/core/src/test/java/org/lfenergy/shapeshifter/core/model/PayloadMessageFixture.java b/core/src/test/java/org/lfenergy/shapeshifter/core/model/PayloadMessageFixture.java
index f1a2048..229f38a 100644
--- a/core/src/test/java/org/lfenergy/shapeshifter/core/model/PayloadMessageFixture.java
+++ b/core/src/test/java/org/lfenergy/shapeshifter/core/model/PayloadMessageFixture.java
@@ -4,7 +4,11 @@
 
 package org.lfenergy.shapeshifter.core.model;
 
-import org.lfenergy.shapeshifter.api.*;
+import org.lfenergy.shapeshifter.api.AvailableRequestedType;
+import org.lfenergy.shapeshifter.api.FlexRequest;
+import org.lfenergy.shapeshifter.api.FlexRequestISPType;
+import org.lfenergy.shapeshifter.api.FlexRequestResponse;
+import org.lfenergy.shapeshifter.api.TestMessage;
 
 import java.time.Duration;
 import java.time.OffsetDateTime;
@@ -49,6 +53,16 @@ public static FlexRequest createTestFlexRequest(String messageId, String senderD
         return flexRequest;
     }
 
+    public static FlexRequestResponse createTestFlexRequestResponse(String messageId, String senderDomain, String recipientDomain) {
+        var flexRequestResponse = new FlexRequestResponse();
+        flexRequestResponse.setMessageID(messageId);
+        flexRequestResponse.setConversationID(CONVERSATION_ID);
+        flexRequestResponse.setSenderDomain(senderDomain);
+        flexRequestResponse.setRecipientDomain(recipientDomain);
+        flexRequestResponse.setTimeStamp(NOW);
+        return flexRequestResponse;
+    }
+
     public static TestMessage createTestMessage(String messageId, String senderDomain, String recipientDomain) {
         var testMessage = new TestMessage();
         testMessage.setMessageID(messageId);
diff --git a/core/src/test/java/org/lfenergy/shapeshifter/core/model/UftpMessageFixture.java b/core/src/test/java/org/lfenergy/shapeshifter/core/model/UftpMessageFixture.java
index dd398a4..1d476a3 100644
--- a/core/src/test/java/org/lfenergy/shapeshifter/core/model/UftpMessageFixture.java
+++ b/core/src/test/java/org/lfenergy/shapeshifter/core/model/UftpMessageFixture.java
@@ -4,6 +4,7 @@
 
 package org.lfenergy.shapeshifter.core.model;
 
+import org.lfenergy.shapeshifter.api.PayloadMessageResponseType;
 import org.lfenergy.shapeshifter.api.PayloadMessageType;
 
 public final class UftpMessageFixture {
@@ -15,6 +16,9 @@ private UftpMessageFixture() {
   public static <T extends PayloadMessageType> UftpMessage<T> createIncoming(UftpParticipant sender, T payloadMessage) {
     return new UftpMessage<>(sender, UftpMessageDirection.INCOMING, payloadMessage);
   }
+  public static <T extends PayloadMessageResponseType> UftpMessage<T> createIncomingResponse(UftpParticipant sender, T payloadMessage) {
+    return new UftpMessage<>(sender, UftpMessageDirection.INCOMING, payloadMessage);
+  }
 
   public static <T extends PayloadMessageType> UftpMessage<T> createOutgoing(UftpParticipant sender, T payloadMessage) {
     return new UftpMessage<>(sender, UftpMessageDirection.OUTGOING, payloadMessage);
diff --git a/core/src/test/java/org/lfenergy/shapeshifter/core/service/sending/UftpSendMessageServiceTest.java b/core/src/test/java/org/lfenergy/shapeshifter/core/service/sending/UftpSendMessageServiceTest.java
index b19f75a..9f24923 100644
--- a/core/src/test/java/org/lfenergy/shapeshifter/core/service/sending/UftpSendMessageServiceTest.java
+++ b/core/src/test/java/org/lfenergy/shapeshifter/core/service/sending/UftpSendMessageServiceTest.java
@@ -65,7 +65,6 @@ class UftpSendMessageServiceTest {
   @Mock
   private UftpValidationService uftpValidationService;
 
-
   private UftpSendMessageService testSubject;
 
   @Mock
diff --git a/core/src/test/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidatorTest.java b/core/src/test/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidatorTest.java
new file mode 100644
index 0000000..ebeb45d
--- /dev/null
+++ b/core/src/test/java/org/lfenergy/shapeshifter/core/service/validation/base/ReferencedRequestMessageIdInResponseValidatorTest.java
@@ -0,0 +1,82 @@
+package org.lfenergy.shapeshifter.core.service.validation.base;
+
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.lfenergy.shapeshifter.api.FlexRequest;
+import org.lfenergy.shapeshifter.api.FlexRequestResponse;
+import org.lfenergy.shapeshifter.api.PayloadMessageResponseType;
+import org.lfenergy.shapeshifter.api.TestMessageResponse;
+import org.lfenergy.shapeshifter.api.USEFRoleType;
+import org.lfenergy.shapeshifter.core.model.UftpMessageFixture;
+import org.lfenergy.shapeshifter.core.model.UftpParticipant;
+import org.lfenergy.shapeshifter.core.service.validation.UftpMessageSupport;
+import org.mockito.InjectMocks;
+import org.mockito.Mock;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.util.Optional;
+import java.util.UUID;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.BDDMockito.given;
+
+@ExtendWith(MockitoExtension.class)
+class ReferencedRequestMessageIdInResponseValidatorTest {
+    private static final String FLEX_REQUEST_MESSAGE_ID = UUID.randomUUID().toString();
+    private static final String CONVERSATION_ID = UUID.randomUUID().toString();
+    @Mock
+    private UftpMessageSupport messageSupport;
+
+    @InjectMocks
+    private ReferencedRequestMessageIdInResponseValidator testSubject;
+
+    private final UftpParticipant sender = new UftpParticipant("example.com", USEFRoleType.DSO);
+    private final PayloadMessageResponseType flexRequestResponse = new FlexRequestResponse();
+    private final FlexRequest flexRequest = new FlexRequest();
+
+    @Test
+    void appliesTo() {
+        assertThat(testSubject.appliesTo(FlexRequestResponse.class)).isTrue();
+    }
+
+    @Test
+    void notAppliesTo() {
+        assertThat(testSubject.appliesTo(TestMessageResponse.class)).isFalse();
+    }
+
+    @Test
+    void valid_whenNoFlexRequestReferenceInResponse() {
+        ((FlexRequestResponse) flexRequestResponse).setFlexRequestMessageID(null);
+
+        assertThat(testSubject.isValid(UftpMessageFixture.createIncomingResponse(sender, flexRequestResponse))).isFalse();
+    }
+
+    @Test
+    void valid_whenFlexRequestReferenceInResponseIsKnown() {
+        var uftpMessage = UftpMessageFixture.createIncomingResponse(sender, flexRequestResponse);
+
+        ((FlexRequestResponse) flexRequestResponse).setFlexRequestMessageID(FLEX_REQUEST_MESSAGE_ID);
+        flexRequestResponse.setConversationID(CONVERSATION_ID);
+        given(messageSupport.findReferencedMessage(uftpMessage.referenceToPreviousMessage(FLEX_REQUEST_MESSAGE_ID, CONVERSATION_ID,
+                FlexRequest.class))).willReturn(Optional.of(flexRequest));
+
+        assertThat(testSubject.isValid(uftpMessage)).isTrue();
+    }
+
+    @Test
+    void invalid_whenReferenceInResponseIsNotKnown() {
+        var uftpMessage = UftpMessageFixture.createIncomingResponse(sender, flexRequestResponse);
+
+        ((FlexRequestResponse) flexRequestResponse).setFlexRequestMessageID(FLEX_REQUEST_MESSAGE_ID);
+        flexRequestResponse.setConversationID(CONVERSATION_ID);
+        given(messageSupport.findReferencedMessage(uftpMessage.referenceToPreviousMessage(FLEX_REQUEST_MESSAGE_ID, CONVERSATION_ID,
+                FlexRequest.class))).willReturn(Optional.empty());
+
+        assertThat(testSubject.isValid(uftpMessage)).isFalse();
+    }
+
+    @Test
+    void getReason() {
+        assertThat(testSubject.getReason()).isEqualTo("Unknown reference Request message ID");
+    }
+}