diff --git a/src/cas/os/posixRT/osiMutex.h b/src/cas/os/posixRT/osiMutex.h
new file mode 100644
index 000000000..2299cb996
--- /dev/null
+++ b/src/cas/os/posixRT/osiMutex.h
@@ -0,0 +1,45 @@
+//
+// osiMutex - OS independent mutex 
+// (posix RT version)
+//
+
+#include <semaphore.h>
+#include <assert.h>
+
+class osiMutex {
+public:
+	//
+	// constructor that returns status
+	// (since g++ does not have exceptions)
+	//
+	caStatus osiMutexInit()
+	{
+		int status;
+		status = sem_init(&this->sem,0,0);		
+		if (status) {
+			return -1;
+		}
+		return 0;
+	}
+	~osiMutex()
+	{
+		int status;
+		status = sem_destroy(&this->sem);		
+		assert(status==0);
+	}
+        void lock() 
+	{
+		int status;
+		status = sem_wait(&this->sem);		
+		assert(status==0);
+	}
+        void unlock() 
+	{
+		int status;
+		status = sem_post(&this->sem);		
+		assert(status==0);
+	}
+private:
+	sem_t	sem;
+};
+