TiO2/Bi2S3 heterojunctions with a nuclear-shell structure were prepared by the coprecipitation method. The products were characterized by X-ray diffraction analysis, Raman spectra, transmission electron microscope images and energy dispersion X-ray spectra. Results showed that as-prepared Bi2S3 was urchin-like, made from many nanorods, and TiO2/Bi2S3 heterojunctions have a similar nuclear-shell structure, with Bi2S3 as the shell and TiO2 as the nuclear. The photocatalytic experiments performed under UV irradiation using methyl orange as the pollutant revealed that the photocatalytic activity of TiO2 could be improved by introduction of an appropriate amount of Bi2S3. However, excessive amount of Bi2S3 would result in the decrease of photocatalytic activity of TiO2. The relative mechanism was proposed. (C) 2012 Elsevier Ltd. All rights reserved.