1000 nm-thick Au film was sputter-deposited on two groups of nickel alloy substrates, in which one group (Group A) was oxidated at 800 degrees C for 20 h to form a oxide film before coating gold while another group (Group B) was unoxidated. The gold thin-film is applied to serve as a low emissivity coating to reflect thermal radiation. The gold-coated samples were heated in air at 600 degrees C for 150 h to explore the effect of high-temperature environment on the emissivity of coated Au film. After heat-treatment, the average thermal emissivity at the wavelength of 3-14 mu m of Group B greatly increased from 0.18 to 0.82 while that of Group A only increased a little. The diffusion between Au and other nickel alloy elements at 600 degrees C also had been discussed in this paper. (C) 2008 Elsevier B.V. All rights reserved.