Cocatalyst modification is an efficient strategy to improve the photocatalytic efficiency of photocatalysts by promoting the effective separation of photogenerated electrons and holes. However, most of the cocatalysts are restricted to noble metals (e.g., Ag, Au, Pt) and seldom investigation has been focused on their oxides. In this study, Ag2O cocatalyst was coated on the surface of Bi2WO6 nanoparticles by an impregnation method followed by a low-temperature treatment (100-350 degrees C) and their photocatalytic performance was evaluated by the photocatalytic decolorization of methyl orange solution under visible-light irradiation. It was found that after the surface coating of Ag2O, the obtained Ag2O/Bi2WO6 composites exhibited an obvious higher photocatalytic activity than the unmodified Bi2WO6 nanoparticles and N-doped TiO2. Owing to the photosensitive property of pure Ag2O phase, the Ag-Ag2O composite easily formed during the decomposition process of organic substances under visible-light irradiation. On the bases of experimental result and band structure analysis, an Ag-Ag2O cocatalyst-enhanced photocatalytic mechanism is proposed; namely, the Ag-Ag2O cocatalyst possibly reduces oxygen via a multi-electron transfer mechanism. The present results suggest that Ag-Ag2O can act as a new and effective cocatalyst for the enhanced photocatalytic performance of photocatalysts, which provides a new approach for the design and development of high-performance visible-light photocatalysts. (C) 2011 Elsevier B.V. All rights reserved.