Nanocrystal TiO2 films were prepared by radio frequency (RF) sputtering technique and coating method, respectively. The samples were treated by Ar RF plasma. The crystal structure, absorption spectra and morphology of the TiO2 films were investigated by X-ray diffraction (XRD), UV-VIS spectrophotometry and atomic force microscopy (AFM). The voltages and photo-currents of the TiO2 electrodes were also measured. By Ar plasma treatment, the photocurrents of the sputtered and coated TiO2 electrodes increased by 80% and 60%, respectively. (c) 2004 Elsevier B.V. All rights reserved.