Forward biasing of transparent nanocryst. TiO2 (anatase) films in Li ion contg. org. electrolytes leads to rapid and reversible coloration due to electron accumulation and Li+ intercalation in the anatase lattice. Absorption of > 90% light throughout the visible and near IR can be switched on and off within a few seconds. The nanocryst. morphol. of the film plays a primordial role in enhancing the electrochromic process. Preliminary results from the redn. of a surface attached viologen mol. leading to a blue coloration of the film are reported.