Efficient hydrogen production and decomposition of glycerol were achieved on CuO-modified titania (CuO-TiO2) photocatalysts in glycerol aqueous solutions. CuO clusters were deposited on the titania surface by impregnation of Degussa P25 TiO2 powder (P25) with copper nitrate followed by calcination. The resulting CuO-TiO2 composite photocatalysts were characterized by X-ray diffraction (XRD), UV-visible spectrophotometry, X-ray photoelectron spectroscopy (XPS), N-2 adsorption-desorption, transmission electron microscopy (TEM) and photoluminescence (PL) spectroscopy. The low-power ultraviolet light emitting diodes (UV-LED) were used as the light source for photocatalytic H-2-production reaction. A detailed study of CuO effect on the photocatalytic H-2-production rates showed that CuO clusters can act as an effective co-catalyst enhancing photocatalytic activity of TiO2. The optimal CuO content was found to be 1.3 wt.%, giving H-2-production rate of 2061 mu mol h(-1) g(-1) (corresponding to the apparent quantum efficiency (QE) of 13.4% at 365 nm), which exceeded the rate of pure TiO2 by more than 129 times. The quantum size effect of CuO clusters is deemed to alter its energy levels of the conduction and valence band edges in the CuO-TiO2 semiconductor systems, which favors the electron transfer and enhances the photocatalytic activity. This work shows not only the possibility of using CuO clusters as a substitute for noble metals in the photocatalytic H-2-production but also demonstrates a new way for enhancing hydrogen production activity by quantum size effect. (C) 2011 Elsevier Inc. All rights reserved.