The effects of temperature and duration of thermal treatments on the microstructure and mechanical properties of electrodeposited gold films were evaluated. Specimens were synthesized by electrodeposition of gold on copper foil substrates followed by application of novel photolithographic and microetching techniques so as to produce a series of free-standing gold thin-films of dimensions 2.5 by 200 by 800 μm supported by copper foil frames. Seven different heat treatments, spanning temperatures from 25 to 300°C and up to 8 h in duration, were studied. In each case, thermal annealing of the samples was carried out in an inert atmosphere after the copper foil substrate beneath the tensile coupons had been removed by CuCl² etchants. X-ray diffraction was used to assess the microstructures. The crystalline texture of the films changed from predominantly <111> (perpendicular to the plane) to strongly <100>, and then back toward <111> with heat treatment. No evidence for grain growth was seen in the X-ray diffraction results. Tensile-strength analyses were performed using a piezo-actuated microtensile testing system. The properties of the heat-treated specimens varied significantly from those of the nontreated material. Tensile strength generally decreased with longer heat treatment. Cyclic fluctuations in the elongation-to-failure, strikingly similar to those in the ratio of <200> to <111> diffracted X-ray intensities, were observed as a function of increasing heattreatment temperature.