WO3 has emerged as one of the most extensively studied materials because its gasochromic effect can be used for smart window and gas sensor; currently it is widely used in many energy conservation areas. Compared with other preparations methods for gasoschromic films, sol-gel process shows several advantages, such as low cost and large-scale applications. However, sol-gel WO3 films were not stable enough for commercial application yet. In this paper, we first investigated the effect of SiO2 doping, which exhibited good enhancement of WO3 gasochromic films' stability. We also examined the relationship between SiO2 ratio and stability of WO3/SiO2 films. An empirical formula was established by fitting exponential decay of the coloring-bleaching cycles for four different Si/W ratios.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.