Electrochromic niobium oxide thin films were prepared by chemical vapor deposition. The source material was niobium (V) ethoxide. Amorphous niobium oxide thin films were obtained at a substrate temperature 350-degrees-C. Reduction and oxidation of the films in a 0.1M Na2CO3 + 0.1M NaHCO3 buffer solution resulted in desirable changes in optical absorption. Coulometry indicated that the coloration efficiency was 160 cm2. C-1.