The Ag2S loaded ZnO (Ag2S-ZnO) was successfully synthesized by precipitation of zinc oxalate and Ag2S and calcination of the mixed precipitate at 400 degrees C for 12 h. The catalyst was characterized by X-ray diffraction (XRD), high resolution scanning electron microscope (HR-SEM) images, energy dispersive spectra (EDS), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV). X-ray photoelectron spectroscopy (XPS) and BET surface area measurements. XPS reveals that all the Ag in the catalyst are present in the form of Ag+ before irradiation. The photocatalytic activity of Ag2S-ZnO was investigated for the degradation of Acid Black 1 (AB 1) in aqueous solution using solar light. Ag2S-ZnO is found to be more efficient than commercial ZnO, prepared ZnO, TiO2-P25 and TiO2(Merck) at pH 9 for the mineralization of AB 1. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of AB 1 have been analyzed. The mineralization of AB 1 has been confirmed by COD measurements. The catalyst is found to be reusable. (C) 2012 Elsevier BM. All rights reserved.