Ta-doped TiO2 and Au/TiO2 nanocomposite thin films were successfully synthesized by co-sputtering. The Ta-doped TiO2 films formed a solid solution that induced structural changes from rutile to anatase phases. In the Au/TiO2 nanocomposite films, Au particles with a diameter of about 15 nm were homogeneously distributed in the TiO2 matrix. The anodic photocurrents of the Ta-doped TiO2 electrodes and Au/TiO2 nanocomposite electrodes were observed not only in the UV but also in the visible light range. The photoresponse in visible light between Ta-doped TiO2 and Au/TiO2 nanocomposite are due to bandgap reduction and photoexcitation of electrons from the interface states. (C) 2004 The Electrochemical Society.