[en] Electrochromic behavior has been studied by potentiostatic and galvanostatic measurements on sputtered amorphous films in the systems Li/sub 2/O-WO/sub 3/Nb/sub 2/O/sub 5/ and WO/sub 3/-Nb/sub 2/O/sub 5/. The bleaching of films containing Li/sub 2/O was complete, whereas the films without Li/sub 2/O showed a residual color. The kinetics of bleaching in the Li/sub 2/O-WO/sub 3/-Nb/sub 2/O/sub 5/ films was ascribed to a space-charge-limited current flow, while that of WO/sub 3/-Nb/sub 2/O/sub 5/ films could not be explained by a space-charge-limited current model. Such a difference in electrochromic properties is caused by the addition of Li/sub 2/O, which increases the conductivity of Li/sup +/ ions in the films