Titanium dioxide co-doped with yttrium and nitrogen with different yttrium doping concentration has been synthesized by mild one pot hydrothermal method without any post calcination for crystallization. Irrespective of the yttrium doping concentration, all the synthesized samples were composed of pure anatase phase with good crystallinity. And the synthesized co-doped samples have spherical morphology with uniform particle size distribution. The absorption edge of the co-doped TiO2 was shifted toward visible light region depicting that the intrinsic band gap of TiO2 was affected by the co-doping. Among the different samples, the co-doped sample with 0.05% yttrium doping concentration exhibits enhanced visible light photocatalytic activity by degradation of methylene blue in aqueous solution. Compensated and non-compensated yttrium-nitrogen co-doped TiO2 models were simulated using density functional theory to explain the experimental findings. The calculation results show that the compensated yttrium-nitrogen co-doped TiO2 model may reasonably explain the experimental observations due to its stable configuration, narrowed band gap and enhanced separation of photoexcited carriers. (C) 2013 Elsevier Ltd. All rights reserved.