Abstract: Molybdenum oxide films were fabricated successfully by spin coating from Li＋doped peroxopolymolybdate solution via solgel technique.Their electrochemical and electrochromic properties were investigated by cyclic voltammetry and insitu UV transmittance measurements.The results showed that the films possessed excellent electrochemical stability and reversibility.The electrochromic mechanism of the MoO3 was discussed by using results obtained from Xray photoelectron spectroscopy (XPS).The results showed that the most part of the Mo6＋ in MoO3 film was reduced to Mo5＋ and Mo4＋ ions during the Li＋ intercalation process,Mo4＋ was oxidized to Mo5＋ and part of Mo5＋ was oxidized to Mo6＋ again during the Li＋ deintercalation process.So it was considered that Mo4＋ ions existed in the colored MoO3 films.

Key words: MoO₃ films, Electrochromic, X-ray photoelectron spectroscopy (XPS)