The composites of Co3O4/reduced graphene oxide nanosheets (Co3O4/rGONS) are prepared via a facile hydrothermal route followed by calcination, of which the morphology and microstructure are characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It is found that the as-obtained Co3O4 nanosheets on which many fine nanoparticles are homogeneously assembled aggregate in a flower shape on the surfaces of reduced graphene oxide. Electrochemical properties are investigated using cyclic voltammetry and galvanostatic charge/discharge in 1 M KOH aqueous solution. In comparison with pure Co3O4, the specific capacity and redox performance of the as-made Co3O4/rGONS composites have been significantly improved, which are mainly attributed to the composite structure with high porosity formed due to the interaction of Co3O4 and reduced graphene oxide nanosheets during the fabrication process of the Co3O4/rGONS nanocomposites. The Co3O4/rGONS-II shows good cyclic performance and coulomb efficiency with a specific capacitance over 400 F g(-1) at a current density of 0.5-2.0 A g(-1). (C) 2013 Elsevier Ltd. All rights reserved.