Abstract: An electromechanical compression release valve for compressors, engines with rotary or reciprocating mechanisms and external combustion engines, such as, a Stirling cycle engine, reduces the engine starting power by reducing the compression pressure in the cylinder head space area. The valve reduces the compression pressure by passing the working fluid from the cylinder head space to another compartment. The valve comprises a housing, a valve member, a valve-driving member, a valve position sensor, and a ratchet pawl. In the open position, and while starting the engine, the inlet of the rotatable valve member is aligned with the opening in a chamber connected to the engine work space, thus, the working fluid passes through the valve member into the crankcase. After the engine starts, the valve position sensor directs the valve-driving member to rotate the valve member to the closed position. When closed, the engine working fluid can now achieve the operating compression pressures.