The actuation voltage of microelectromechanical system (MEMS) metal switches was investigated at temperatures ranging from 10 to 290 K. The investigation shows a 50% increase in the actuation voltage at low temperature. A comparison has been made using a published model and showed similar increment of actuation voltage at low temperature.Introduction: Over the past few years, radio-frequency microelectromechanical systems (RF MEMS) fabricated using semiconductor micro-fabrication technology have gained significant interest for wireless communication applications owing to their small size, integration capability and superior performance. For instance, using RF MEMS switches, RF circuits such as variable capacitors, tunable filters, phase shifters and signal routers have been demonstrated [1]. Recently, there has been research interest in the application of the high-Tc superconductor (HTS) in combination with RF MEMS devices. A switched HTS microstrip resonator and a tunable HTS filter, both incorporating MEMS technology, have been demonstrated [2,3]. While successful integration of MEMS switches onto HTS devices is a challenging task, the operational issue of RF MEMS switches at low temperatures is another key consideration to many microwave and system designers. In fact, there has been little literature reporting the behaviour of MEMS switches at cryogenic temperature. In this Letter, we report our recent findings on low temperature measurements of MEMS metal switches.