ZrS2-loaded ZnO (ZrS2-ZnO) nano-composites were synthesized by the precipitate-thermal decomposition method. The coexistence of ZrS2 increased the absorbance of ZnO in UV region. X-ray photoelectron spectroscopic analysis revealed Zr in the form of Zr4+. The prepared catalysts were used for degradation of an industrial pollutant azo dye, naphthol blue black (NBB), under UV light. It was found that the uptake of 11.4 wt% ZrS2 on ZnO was very efficient for NBB removal and its photocatalytic activity was more efficient than ZnO, ZrS2 and TiO2 catalysts. The optimum pH for efficient degradation of NBB was 6.5. Based on the energy levels of ZrS2 and ZnO, a mechanism was proposed for the higher efficiency of ZrS2-ZnO under UV light. This catalyst was reusable. (C) 2014 Elsevier B.V. All rights reserved.