Graphite oxide/Co(OH)(2) layered composites are prepared by nanosheet assembling between the exfoliated Co(OH)(2) and graphene oxide (GO) nanosheets. The subsequent thermal treatment of GO/Co(OH)(2) composites in controlled atmospheres converts GO into reduced graphene oxide (RGO) and Co(OH)(2) into Co3O4. The RGO/Co3O4 hybrid nanocomposites with different amounts of Co3O4 are thoroughly characterized, and their electrochemical properties as supercapacitor electrode are systematically investigated by cyclic voltammetry, galvanostatic charge-discharge, and electrochemical impedance spectroscopy in the KOH electrolyte. In particularly, the RGO/Co3O4 hybrid composite with 94.3 wt% Co3O4 exhibits a high specific capacitance of 331 F g(-1) at the current density of 5 A g(-1), and shows the excellent electrochemical cycle stability with capacitance retention over 122% after 5000 continuous charge-discharge cycles. These outstanding capacitive performances make the RGO/Co3O4 hybrid nanocomposites one of the promising candidates for the supercapacitor electrode. (C) 2013 Elsevier Ltd. All rights reserved.