Nanosized W-doped TiO2 photocatalysts were synthesized by a simple hydrothermal method, and characterized by energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), transmission electron microscopy (TEM) and BET surface area analyzer. The photocatalytic activity of undoped TiO2 and W-doped TiO2 photocatalysts was evaluated by the photocatalytic oxidation degradation of methyl orange in aqueous solution. The results show that the photocatalytic activity of the W-doped TiO2 photocatalyst is much higher than that of undoped TiO2, and the optimum percentage of W doped is 2.0 mol%. The enhanced photocatalytic activity of the doped photocatalyst may be attributed to the increase in the charge separation efficiency and the presence of surface acidity. (C) 2008 Elsevier B.V. All rights reserved.