BaCrO4 and SrCrO4 photocatalyst powders were prepared by the solid state reaction method. They were characterized by powder X-ray diffraction, UV-Vis diffuse reflection spectroscopy and photocatalytic activity measurements in case of sacrificial reagents CH3OH and AgNO3 Under UV and visible light irradiation (lambda > 420 nm), respectively. The band gaps of BaCrO4 and SrCrO4 were determined as 2.63 and 2.44 eV. Due to the decrease of the ionic radius of the cation, the photocatalyst SrCrO4 showed much lower photocatalytic activity than BaCrO4 in evolving H-2 from CH3OH/H2O solution. The difference in their photocatalytic activity is ascribed to the special electronic structures of BaCrO4 and SrCrO4. (C) 2003 Elsevier B.V. All rights reserved.