A novel photocatalyst Ag2SO3 was prepared and the effect of Ag nanoparticles, photo-deposited on the surface of Ag2SO3, on its photocatalytic activity was investigated. The as-prepared photocatalyst was characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-vis diffuse reflection spectroscopy (DRS). The photocatalytic activity was evaluated by photo-degradation of rhodamine B dye under UV light irradiation. It was found that the photocatalytic activity of Ag2SO3 was initially enhanced with deposition of Ag nanoparticles, but subsequently declined with Ag nanoparticles overloaded. The possible mechanism was proposed based on experimental results. These findings may contribute to developing novel photocatalysts and understanding of fundamentals of Ag-based photocatalytic materials. (C) 2015 Elsevier Ltd. All rights reserved.