Visible-light irradiation to monoclinic scheelite BiVO4 (m-BiVO4) in a solution of copper acetylacetonate (Cu(acac)(2)) has led to its decomposition and Cu recovery. The photonic efficiency at lambda = 440 +/- 15 nm reaches 3.4%, exceeding the value for the TiO2-photocatalyzed reaction at lambda = 355 +/- 23 nm (2.0%). The adsorption isotherm and the light intensity-dependence of the decomposition rate indicate high adsorptivity of m-BiVO4 for Cu(acac)(2) or its sufficient supply to the surface reaction sites, which mainly contributes to the high photocatalytic activity. Electrochemical measurements using cyclic voltammetry suggest that the reaction proceeds via the oxidative degradation of the ligand followed by the reduction of the resulting Cu2+ ions. Under aerobic conditions, the Cu2+ ions mediate the electron transfer from the conduction band of m-BiVO4 to O-2 to complete the catalytic cycle.