In this work, we detail the synthesis of a highly active hybrid photocatalyst composed of reduced graphene oxide (RGO) and zinc oxide spheres (ZnO SPs) by a facile and fast microwave-assisted solvothermal reaction, where the reduction of graphene oxide (GO) and growth of ZnO SPs occur in one pot. Under visible light illumination, the fabricated RGO-ZnO SP nanocomposite exhibited a 10-fold higher photocatalytic activity when compared to that of pure ZnO and RGO alone. Such an improvement can be attributed to an increase in the absorption of visible light, a decrease in the band gap, and effective charge transfer among the methylene blue (MB), RGO, and ZnO. In addition, the fabricated RGO-ZnO SP showed good stability even after four repeated photocatalytic reactions, which indicates synergetic effects induced via hybridization between the RGO and ZnO. We believe that this type of hybrid material can be effectively used as a highly active and stable photocatalyst to remove various pollutants. (C) 2013 Elsevier B.V. All rights reserved.