TiO2 thin films were prepared by the inductively coupled Ar+-plasma sputtering method. The effects Of O-2 partial pressure on photoelectrochemical performance of the mainly anatase-TiO2 electrodes were studied. O-2 partial pressure systematically affected the carrier density and the current-voltage characteristics of the electrodes. An electrode deposited at lowest O-2 partial pressure (11 mPa) showed almost 3 orders of magnitude greater donor density and 4 times larger photocurrent compared to the one deposited at highest O-2 partial pressure (52 mPa). The differences in current-voltage characteristics of the electrode samples are discussed on the basis of the space charge layer formation in the electrodes with different carrier densities. (c) 2005 Elsevier B.V All rights reserved.