Molybdenum oxide (MoO3) films were prepared by the sol-gel process, using a lithium-doped peroxo-polymolybdate precursor solution. The highest quality films were obtained from precursor solutions containing 10% lithium. The structural properties of the films were characterized by TG-DTA and FTIR. The electrochemical and electrochromic properties were measured by cyclic voltammetry and an in-situ transmittance technique in 1 M LiClO4/propylene carbonate electrolyte. The results show that the Li-doped MoO3, films possess excellent electrochemical stability and reversibility, a remarkable change of transmittance (Delta T = 32.3%) in visible region after coloration, and good electrochromic performance.