In this study ZnO@Ag2S core shell nanoparticles (CSNPs) were synthesized by a chemical approach at a relatively low temperature of around 60 degrees C. The shell material was obtained by transferring a ZnS shell synthesized at around bare a ZnO nanoparticles (NPs) to Ag2S. This transfer was achieved at temperature of around 60 degrees C owing to the relatively low value of the solubility product constant of Ag2S compared to that of ZnS. The as-grown ZnO@Ag2S core shell NPs were used as a photocatalyst to degrade Eriochrome black-T dye. Since dye pollutants can be found in mediums with different pH, the degradation experiments were performed at basic and acidic pH values. Photo-decolonization experiments of Eriochrome black-T dye indicated that the ZnO@Ag2S CSNPs act more efficiently as a photcatalyst for both acidic and basic pH values compared to bare ZnO NPs. Then the reusability of the nano-catalyst was tested to confirm that it can be applied as an effective and recyclable photocatalyst. (C) 2015 Elsevier B.V. All rights reserved.