Tetragonal and monoclinic bismuth vanadate (BiVO4) powders were selectively synthesized by aqueous processes. The characterizations of the as-prepared BiVO4 powders were carried out by X-ray diffraction, nitrogen adsorption, scanning electron microscopy and UV-vis diffuse reflectance spectroscopy. The photocatalytic activities of different BiVO4 samples were determined by degradation of methylene blue solution under visible-light irradiation (lambda > 420 nm) and compared with that of TiO2 (Degussa P25). The band gaps of the as-prepared BiVO4 were determined from UV-vis diffuse reflectance spectra. It was found that monoclinic BiVO4 with a band gap of 2.34 eV showed higher photocatalytic activity than that of tetragonal BiVO4 with a band gap of 3.11 eV. (C) 2007 Elsevier B.V. All rights reserved.