Electronic components including switches that can operate at elevated temperatures in excess of 200 °C are under development for applications such as the More Electric Aircraft. SiC is utilized to build high temperature switches, but limitations in fabrication techniques have stunted the development of SiC based devices. Other wide band gap materials such as diamond offer the promise of meeting the high temperature requirements. A new class of high voltage, high power, high temperature diamond switches was developed under a Phase II STTR program from the US Air Force. A 1000 V, 156 A diamond switch was operated at temperatures up to 375 °C to demonstrate the validity of these switches for More Electric Aircraft applications. Designs for a practical switch were completed. Such a 1000 V/1000 A diamond switch operating at 400 °C would have a <5 V forward voltage drop.