The Zr co-doped Ag-ZnO (Zr-Ag-ZnO) was successfully synthesized by precipitation decomposition method. The photocatalytic activity of Zr-Ag-ZnO was investigated for the degradation of Acid Black 1 (AB 1) in aqueous solution using UV-A light. Co-dopants shift the absorbance of ZnO, both in UV and visible region. Zr-Ag-ZnO is found to be more efficient than Ag-ZnO, Zr-ZnO, commercial ZnO, prepared ZnO, TiO2-P25 and TiO2 (Merck) at pH 9 for the mineralization of AB 1 under UV-A light. The influence of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of AB 1 has been analyzed. The mineralization of AB 1 has been confirmed by COD measurements. Mechanism of degradation by Zr-Ag-ZnO is proposed. The catalyst is found to be reusable. (C) 2013 Elsevier B.V. All rights reserved.