A series of copper-deposited titania were prepared by photoreduction method under irradiation with a 125-W high-pressure mercury lamp. From XPS and AES results, the deposited-copper formed Ti-O-Cu bond on the surface of TiO(2), and the Cu species on the surface of copper-deposited TiO(2) can be identified as Cu(I). The photocatalytic degradation activity of methylene blue for the Cu(2)O-TiO(2) series increased with increasing Cu(2)O-deposited content, and then decreased. The highest photocatalytic degradation activity of methylene blue was obtained for 0.16% Cu(2)O-TiO(2),. When copper-deposited content reached to 0.32%, the photocatalytic activity was lower than that of pure TiO(2). It is shown that Cu(2)O on the surface of TiO(2) can trap electrons from the TiO(2) conduction band, and the electrons trapped on the Cu(2)O-TiO(2) site are subsequently transferred to the surrounding adsorbed O(2), thereby avoiding electron-hole recombination, and enhancing the photocatalytic activity. Excess copper loading may screen the photocatalyst from the UV source, so the photocatalytic activity diminishes with increasing Cu(2)O. (C) 2008 Elsevier Ltd. All rights reserved.