AgI doped SnO2 nano-composites were prepared by the chemical coprecipitation method and were characterized by the X-ray diffraction, transmission electron microscopy and X-ray photoelectron spectroscopy. Results showed that main of the I- ions remained in the AgI lattice which is highly dispersed in the system. The photo-catalytic experiments performed under visible light irradiation using methylene blue as the pollutant revealed that not only the photo-catalytic activity but also the stability of SnO2 based photocatalyst could be improved by introduction of an appropriate amount of AgI, and the result was further supported by the UV-Vis diffuse reflection spectra and the electron spin-resonance spectra. Among all of the samples, AgI-SnO2 nano-composite with 2At% AgI exhibited the best catalytic efficiency and stability. (C) 2013 Elsevier Ltd. All rights reserved.