In this study, a novel visible-light-responsive PbSe-TiO2 nanocomposite photocatalysts were successfully synthesized through a facile sonochemical-assisted method, and characterized by XRD, SEM-EDX, TEM, and DRS to confirm its structure, morphology, composition, and optical property. In decolorization of rhodamine B, a significant enhancement in the reaction rate was observed with PbSe TiO2 composite, compared to the pure TiO2. The generation of reactive oxygen species was detected through the oxidation reaction from 1,5-diphenyl carbazide (DPCI) to 1,5-diphenyl carbazone (DPCO). The high photocatalytic activity can be attributed to the synergetic effect of PbSe nanoparticles and TiO2 by extending the spectral response of TiO2 to visible region and also help to reduce the charge recombination. Finally, the possible mechanism for generation of reactive oxygen species under visible light irradiation was proposed as well. (C) 2015 Elsevier B.V. All rights reserved.