Polycrystalline TiO2-x pellets were equilibrated at 1220-1420 K in a flow of Ar + 7 vol. % H-2 gas mixture. The resulting deviation x from stoichiometric composition of titanium dioxide was determined gravimetrically. X-ray diffractometry revealed coexistence of rutile with TinO2n-1 Magneli phases. Optical reflectance and photocurrent spectroscopies served as experimental methods of the band gap determination. Polycrystalline TiO2-x were used as photoanodes in a photoelectrochentical cell. The photocurrent response to the applied voltage was studied. It was found that TiO2-x with x ca. 0.006 exhibited the best photoelectrochemical performance. (c) 2007 Elsevier B.V. All rights reserved.