Straightforward and scalable fabrications of energy storage electrode materials with high electrochemical performance are of great interest for applications in batteries and supercapacitors. Herein, we report a one-step process for producing high-performance NiO/reduced graphene oxide (RGO) nanocomposites using a ball mill based method, which is simple, environmentally friendly, and cost-effective. Graphite oxide (GO) and nickel power were pulverized in a ball mill, to produce NiO/RGO nanocomposites. GO played an important role in promoting a redox reaction between GO and metallic nickel, which produced a strong bond between the as-formed Ni oxide and RGO. The electrochemical performances of NiO/RGO were investigated by cyclic voltammetry (CV), galvanostatic charge/discharge measurement, and impedance spectroscopy. The NiO/RGO electrodes exhibited high specific capacitance (590 F g(-1) at 1 A g(-1)), a high rate capability (88% retention at a high rate of 15 A g(-1)), and an excellent cycling stability (100% retention after 1000 charge/discharge cycles). (C) 2017 Elsevier B.V. All rights reserved.