The nanocomposites of reduced graphene oxide based nitrogen doped TiO2 (N-TiO2-RGO) and reduced graphene oxide based nitrogen and vanadium co-doped TiO2 (N, V-TiO2-RGO) were prepared via a facile hydrothermal reaction of graphene oxide and TiO2 in a water solvent. In this hydrothermal treatment, the reduction of graphene oxide and the intimate contact between nitrogen doped TiO2 (N-TiO2) or nitrogen and vanadium co-doped TiO2(N, V-TiO2) and the RGO sheet is achieved simultaneously. Both N-TiO2-RGO and N, V-TiO2-RGO nanocomposites exhibit much higher visible light photocatalytic activity than N-TiO2 and N, V-TiO2, and the order of visible light photocatalytic activity is N,V-TiO2-RGO>N-TiO2-RGO>N,V-TiO2>N-TiO2>TiO2. According to the characterization, the enhanced photocatalytic activity of the nanocomposites is attributed to reasons, such as enhancement of adsorption of pollutants, light absorption intensity, minimizing the recombination of photoinduced electrons and holes and more excited states of these nanocomposites under visible light irradiation. Overall, this work provides a more marked contrast of graphene based semiconductor nanocomposites and a more comprehensive explanation of the mechanism. (C) 2014 Elsevier B. V. All rights reserved.