Nano-sized yttrium (Y)-doped TiO2 with different Y doping concentrations has been synthesized by hydrothermal method. With pure anatase phase, the as-synthesized samples possess good crystallinity and spherical morphology with uniform particle size distribution. Y doping shifted the absorption edge of TiO2 towards visible light region, as observed from the UV-vis. absorption spectra. XPS (X-ray photoelectron spectroscopy) analysis indicates that Y3+ replaces lattice Ti4+ leading to substitutional point defects. The photocatalytic activity of the synthesized sample was evaluated by the degradation of methylene blue in aqueous solution under visible light irradiations. Y-doped TiO2 shows enhanced photocatalytic activity compared with that of bare TiO2. Compensated and non-compensated density functional theory based calculations were performed for reasonable explanation of the experimental findings. Compensated model with Y3+ replacing Ti4+ along with concomitant presence of an oxygen vacancy might explain the improved photocatalytic activity of Y-doped TiO2. The enhanced photoactivity of Y-doped TiO2 is assigned to the reduced band gap, enhanced visible light absorption and improved separation of electron-hole pairs. (C) 2013 Elsevier B.V. All rights reserved.