Mechanically activated anatase powders were used to assemble thin film electrodes for electrophotocatalytic applications. Flat band potential of the different samples, estimated from the dependence of photopotential on the light intensity, as well as photocurrent vs potential curves were measured at samples milled for different times and compared with those of the untreated anatase. The maximum performance is achieved at samples milled for very short times, at which the mechanical process gives rise to a mixed-phase titania catalyst constituted by anatase and TiO(2)(II) phases. Electrochemical Impedance Spectroscopy measurements were also performed in order to individuate the controlling step of the photoelectrochemical process of water splitting. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.