A valve locking device comprising an intermediate member (18) mountable between a valve body and valve actuator and securable to said valve body and/or actuator; a stem attachment member (20) attachable to and rotatable with a valve stem (14) and contained at least partially within said intermediate member; and an engagement member (22) movably located within said intermediate member for selective engagement with said stem attachment member; whereby in use, engagement between said engagement member and said stem attachment member prevents rotation of said stem attachment member, thus preventing rotation of said valve stem to operate the valve.
