A valve motion measurement assembly is provided for a cylinder valve of an internal combustion engine provided with a valve stem and with a valve head. The valve motion measurement assembly includes a valve position sensor, a supporting bracket provided with at least one sensor seat for the valve position sensor, and a sensor target element configured to be coupled to the valve stem at a distance from the valve head to follow the motion of the cylinder valve. The valve position sensor interacts with the sensor target element for determining the position of the cylinder valve.