Reduced graphene oxide (RGO) sheets decorated by ZnO nanoparticles were synthesized using wet impregnation method. The composite material was characterized by means of X-ray diffraction (XRD), Williamson-Hall Plot (W-H Plot) and Scanning Electron Microscope (SEM) analysis. The XRD pattern revealed orderly hexagonal (wurtzite) structure of the ZnO nanoparticles. Surface morphology of ZnO, RGO and RGO-ZnO was investigated using SEM analysis. SEM images indicated the uniform distribution of ZnO onto the RGO surface. The photocatalytic activity of nanocomposite was demonstrated by determining the degradation of methylene blue dye. The degradation of dye took place due to efficient electron-hole recombination of photo-induced electrons. Finally, plausible mechanism was explained with the help of scavengers. Overall, wet impregnation method was found efficient to produce RGO with uniform ZnO loading. The prepared RGO-ZnO composite can efficiently degrade the dye under UV radiation. (C) 2016 Elsevier B.V. All rights reserved.