Nano-sized doped-metal oxides such as Fe-doped TiO 2, WO 3-doped ZnO and Fe-doped CeO 2 were synthesized by the modified sol-gel/impregnation, flame spray pyrolysis and homogeneous precipitation/impregnation methods respectively. The crystalline phase, particles size, and crystallinity of nano-sized powder were analyzed by X-ray diffraction (XRD) and transmission electron microscopy (TEM). Specific surface area of the sample was examined by the Brunauer, Emmett and Teller (BET) adsorption-desorption of nitrogen gas. The photocatalytic activity of Fe-doped TiO 2, WO 3/ZnO, Fe-doped CeO 2 nanoparticles was examined by studying the mineralization of methanol, sucrose, glucose, oxalic acid and formic acid under UV and visible light irradiations in a pyrex spiral photoreactor. It was found that doped metal oxides could improve the photocatalytic activity of the pure metal oxides. © 2012 Elsevier Ltd. All rights reserved.