A new kind of MoO 3 /Au film was prepared by depositing Au nanoparticles on the surface of MoO 3 thin film through spin-on coating technique. After cathodic polarization, the MoO 3 /Au thin film was found to show enhanced visible-light coloration compared with MoO 3 thin films. The formation of Schottky barrier at the MoO 3 /Au interface, and the visible-light coloration mechanism of the MoO 3 /Au film are elucidated by the energy band theory based on surface photovoltaic spectroscopy measurements.