The electrochromic $WO_3$thin films were prepared by using the electron-beam evaporatin technique. Flms prepared at a vacuum pressure of $10^{-4}$ mbar were found to be most stable during repeated potential cycles. The chemical stability of the film in aqueous solutions was also affected by the vacuum pressure during evaporation. The redox current and the optical properties of the degraded films were affected by the thickness of the film. The 5,000$AA$-thick films were found to be most stable, undergoing the least degradation during the repeated coloring and bleaching cycles. The origin of the mechanism dominating the degradation during the repeated coloring and bleaching cycles was the accumulation of lithium in the film, which results in decreasing redox current. Tungsten oxide films with titanium content of about 10-15 mol% was found to be most stable, undergoing the least degradation during the repeated cycles. The origin of the mechanism dominating the least degradation during the repeated cycles was the reduction of lithium ion trapping sites in the films, which results in a increased durability.