A furnace has been designed which enables one to carry out electron diffraction studies of thin films at high temperatures. Electron diffraction patterns are obtainable at temperatures up to 1100°C. It is possible to bring the furnace up to 1500°C, but at temperatures over 1100°C the photographic plates are fogged by light emitted from the furnace. With the use of this furnace, recrystallizations and phase changes in thin metal and alloy films can be studied at the temperatures where these phenomena occur.