BACKGROUND N-doped TiO2 can narrow the TiO2 forbidden band and thereby increase its catalytic activity under visible light. In this work, three methods (the sol-gel method (SG), the tetrabutyl titanate hydrolysis precipitation method TN', and the H2O2-modified method (TNH)) were used to prepare N-doped TiO2 photocatalysts. The Reactive Red-Violet dye (KN-R) was used as the target pollutant. The catalytic activities of the photocatalysts prepared via the three methods were compared and studied. RESULTS The structures and optoelectronic properties of these catalysts were characterized by various means. The results demonstrated that the N-doped TiO2 catalyst synthesized using the TNH method exhibited the most efficient catalytic activity under visible light and produced a degradation rate of 90% for the Reactive Red-Violet dye. The N-doped TiO2 prepared using the SG method exhibited the lowest catalytic activity under both UV and visible light. The kinetics of photocatalysis degradation for KN-R by N-doped TiO2 prepared by TNH method was studied and found to be zero order due to the good adsorption effect between KN-R and TiO2. CONCLUSION The N-doped TiO2 prepared by TNH method showed good photocatalytic activity in the case of degrading dye under both UV and visible light. (C) 2013 Society of Chemical Industry