The stress of thin (100 nm) gold films grown by electron‐beam deposition onto cover‐glass substrates was measured dynamically during heating and cooling cycles between room temperature and 500 °C. The initial tensile stress, 82 MPa of the as‐deposited films increased slowly with temperature up to about 300 MPa at 375 °C, and then decreased to 120 MPa on further heating to 500 °C. When the film was cooled from 500 °C back to room temperature, the final film stress became compressive (-50 MPa). A transmission electron microscope study has shown that when the temperature is raised above ∼370 °C, which is the eutectic temperature of the gold–silicon binary alloy, an interfacial reaction started between the gold film and the glass substrate. This interfacial reaction can account for the stress relaxation occurring at the high temperatures.