Zn + Mg co-doped TiO2 and the pure TiO2 nanoparticles were prepared by the hydrothermal method. The pure TiO2 and Zn + Mg co-doped TiO2 were analyzed by X-ray photoelectron spectroscopy, X-ray diffraction, transmission electron miscroscopy, energy dispersive X-ray, UV-vis diffuse reflectance absorption spectra. Under a simulated solar light irradiation of 100mW cm(-2), the cell based on doped TiO2 electrode achieved a conversion efficiency of 9.07%, which is noticeably increased by 26.7% compared with undoped TiO2 based DSSC (7.16%). The enhancement of conversion efficiency of the Zn + Mg co-doped TiO2 was attributed to the positive shift of the flat band potentials and fast electron transport in TiO2 films. The mechanism was suggested by intensity modulated photocurrent spectroscopy and intensity modulated photovoltage spectroscopy measurement. (c) 2013 Elsevier Ltd. All rights reserved.