Abstract: Graphene oxide was loaded onto ZnO disks with dominant polar facets and photo-reduced to form ZnO-RGO photocatalysts. Their photocatalytic activity for methylene blue degradation is remarkably improved under UV-visible light irradiation. The enhanced activity is ascribed to the trapping effect of RGO for photoexcited electrons that inhibits electron/hole recombination and to the adsorption effect of RGO for methylene blue to increase its local concentration. The optimal loading of the RGO is ca. 2 mass%, above which light absorption by the RGO decreases the photo utilization efficiency.