Electrodeposition of hydrated TiO2 was performed successfully using an acidic TiCl3 solution on a highly boron-doped diamond (BDD) substrate. The electrochemical and photoelectrochemical properties indicated interesting and improved photocatalytic behavior of n-type TiO2. Scanning electron microscopy showed that the resulting hydrated TiO2 deposits consist of adherent nanomicro-sized particles, scattered on the BDD substrate. The photoelectrocatalytic oxidation of ethanol in a mixture of aqueous 0.1 M HCl and ethanol (1: 1 in volume) showed a clear improvement in the photocurrent, indicating a new TiO2-BDD hybrid system. (c) 2005 The Electrochemical Society.