A series of Se-doped Bi2S3 photocatalysts are prepared using the hydrothermal method. Selenium is doped into Bi2S3 to improve its photocatalytic activity. The obtained products are characterized by X-ray powder diffraction, UV-Vis absorption spectroscopy. X-ray photoemission spectroscopy, and Brunauer-Emmett-Teller surface area analysis. The photocatalytic activities of bare and modified Bi2S3 are studied. Se-doped Bi2S3 shows high photocatalytic activity during the degradation of methylene blue under visible-light irradiation (lambda>400 nm). The effects of different Se contents, synthesis time, temperatures, among others, on photocatalytic activity are discussed. Results show that an appropriate amount of Se dopant can greatly increase photocatalytic activity. Appropriate synthesis times and temperatures are responsible for the obvious increase in photocatalytic activity. (C) 2010 Elsevier B.V. All rights reserved.