ZnO and Ga3+-doped ZnO with different molar ratio of Ga/Zn (1%, 2% and 3%) were prepared by a parallel flow precipitation method. The photocatalysts prepared were characterized by BET surface area, X-ray diffraction (XRD), UV/vis diffuse reflectance spectroscopy (DRS), scanning electron microscope (SEM) and surface photovoltage spectroscopy (SPS), respectively. The results show that doping Ga3+ into ZnO increases the BET surface area. The XRD spectra of the photocatalysts calcined at 573 K show only the characteristic peaks of wurtzite-type. Ga3+-doped ZnO absorbs much more light than ZnO in the visible light region. Doping Ga3+ into ZnO greatly changes the morphology of ZnO and enhances the photoinduced charge separation rate. The photocatalytic activity of ZnO and Ga3+-doped ZnO for decolorization of methyl orange (MO) solution was evaluated, of all the photocatalysts prepared, the Ga3+-doped ZnO with 1% possesses the best photocatalytic activity and the possible reason was discussed. (c) 2012 Elsevier Ltd. All rights reserved.