diff --git a/test_conformance/extensions/cl_khr_semaphore/CMakeLists.txt b/test_conformance/extensions/cl_khr_semaphore/CMakeLists.txt
index 2ef34d3247..5ebda6f2f8 100644
--- a/test_conformance/extensions/cl_khr_semaphore/CMakeLists.txt
+++ b/test_conformance/extensions/cl_khr_semaphore/CMakeLists.txt
@@ -3,6 +3,7 @@ set(MODULE_NAME CL_KHR_SEMAPHORE)
 set(${MODULE_NAME}_SOURCES
          main.cpp
          test_semaphores.cpp
+         test_semaphores_negative_release_retain.cpp
          test_semaphores_negative_getinfo.cpp
          test_semaphores_negative_wait.cpp
          semaphore_base.h
diff --git a/test_conformance/extensions/cl_khr_semaphore/main.cpp b/test_conformance/extensions/cl_khr_semaphore/main.cpp
index f19c5abf2d..7215624580 100644
--- a/test_conformance/extensions/cl_khr_semaphore/main.cpp
+++ b/test_conformance/extensions/cl_khr_semaphore/main.cpp
@@ -47,6 +47,8 @@ test_definition test_list[] = {
                      Version(1, 2)),
     ADD_TEST_VERSION(semaphores_negative_wait_invalid_event_status,
                      Version(1, 2)),
+    ADD_TEST_VERSION(semaphores_negative_release, Version(1, 2)),
+    ADD_TEST_VERSION(semaphores_negative_retain, Version(1, 2)),
 };
 
 const int test_num = ARRAY_SIZE(test_list);
diff --git a/test_conformance/extensions/cl_khr_semaphore/procs.h b/test_conformance/extensions/cl_khr_semaphore/procs.h
index 1ca2195912..cbe3993db5 100644
--- a/test_conformance/extensions/cl_khr_semaphore/procs.h
+++ b/test_conformance/extensions/cl_khr_semaphore/procs.h
@@ -71,3 +71,11 @@ extern int test_semaphores_negative_wait_invalid_event_wait_list(
 extern int test_semaphores_negative_wait_invalid_event_status(
     cl_device_id device, cl_context context, cl_command_queue queue,
     int num_elements);
+extern int test_semaphores_negative_release(cl_device_id device,
+                                            cl_context context,
+                                            cl_command_queue queue,
+                                            int num_elements);
+extern int test_semaphores_negative_retain(cl_device_id device,
+                                           cl_context context,
+                                           cl_command_queue queue,
+                                           int num_elements);
diff --git a/test_conformance/extensions/cl_khr_semaphore/test_semaphores_negative_release_retain.cpp b/test_conformance/extensions/cl_khr_semaphore/test_semaphores_negative_release_retain.cpp
new file mode 100644
index 0000000000..ea6139de28
--- /dev/null
+++ b/test_conformance/extensions/cl_khr_semaphore/test_semaphores_negative_release_retain.cpp
@@ -0,0 +1,89 @@
+//
+// Copyright (c) 2024 The Khronos Group Inc.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//    http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+#include "semaphore_base.h"
+
+#include "harness/errorHelpers.h"
+#include <chrono>
+#include <system_error>
+#include <thread>
+#include <vector>
+
+namespace {
+
+// sema_object is not a valid semaphore object
+
+struct ReleaseInvalidSemaphore : public SemaphoreTestBase
+{
+    ReleaseInvalidSemaphore(cl_device_id device, cl_context context,
+                            cl_command_queue queue)
+        : SemaphoreTestBase(device, context, queue)
+    {}
+
+    cl_int Run() override
+    {
+        // Release invalid semaphore
+        cl_int err = CL_SUCCESS;
+        err = clReleaseSemaphoreKHR(nullptr);
+        if (err != CL_INVALID_SEMAPHORE_KHR)
+        {
+            log_error("Unexpected clReleaseSemaphoreKHR result, expected "
+                      "CL_INVALID_SEMAPHORE_KHR, get %s\n",
+                      IGetErrorString(err));
+            return TEST_FAIL;
+        }
+
+        return TEST_PASS;
+    }
+};
+
+struct RetainInvalidSemaphore : public SemaphoreTestBase
+{
+    RetainInvalidSemaphore(cl_device_id device, cl_context context,
+                           cl_command_queue queue)
+        : SemaphoreTestBase(device, context, queue)
+    {}
+
+    cl_int Run() override
+    {
+        // Release invalid semaphore
+        cl_int err = CL_SUCCESS;
+        err = clRetainSemaphoreKHR(nullptr);
+        if (err != CL_INVALID_SEMAPHORE_KHR)
+        {
+            log_error("Unexpected clRetainSemaphoreKHR result, expected "
+                      "CL_INVALID_SEMAPHORE_KHR, get %s\n",
+                      IGetErrorString(err));
+            return TEST_FAIL;
+        }
+
+        return TEST_PASS;
+    }
+};
+
+}
+
+int test_semaphores_negative_release(cl_device_id device, cl_context context,
+                                     cl_command_queue queue, int num_elements)
+{
+    return MakeAndRunTest<ReleaseInvalidSemaphore>(device, context, queue);
+}
+
+int test_semaphores_negative_retain(cl_device_id device, cl_context context,
+                                    cl_command_queue queue, int num_elements)
+{
+    return MakeAndRunTest<RetainInvalidSemaphore>(device, context, queue);
+}