Three-dimensional nickel oxide/graphene aerogel nanocomposites (NiO/GA) were synthesized via a simple solvothermal-induced self-assembly process. The structural and morphological properties of the NiO/GA were characterized with XRD, FE-SEM and TEM measurements. The nickel oxide was electrochemically deposited into the highly porous GA to form NiO/GA composites. In the three-electrode system, an extremely wide working potential window was observed from −1 to 1V in 6M aqueous KOH. A specific capacitance as high as 587.3Fg−1 was obtained at a constant current density of 1Ag−1. More importantly, the cycling stability of the NiO/GA was great with a tiny decay in specific capacitance after 1000 cycles at 1Ag−1.