NiO/C nanocomposite was prepared directly by means a one-step electrochemical technique based on electrochemical dispergation of nickel by the alternating current. The prepared material was well characterized using different analytical techniques such as X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and N-2 adsorption/desorption. The X-ray diffraction and Raman scattering investigations of the freshly prepared sample confirmed the formation of beta-NiO. The morphology of synthesized NiO/C can be described as dispersed on carbon support nano-leaves consisting of tightly packed array of nanoparticles (around 10 nm in diam) with length of 500-2000 nm and similar to 20 nm thick. NiO/C composite possesses high specific surface area of 137 m(2) g(-1) and a micro-meso-macroporous structure with a distribution of the pore size from 1 to 200 nm. The electrochemical properties of the nanostructured NiO/C were investigated using cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The synthesized NiO/C composite exhibited pseudo-capacitive behavior with the mass capacitance value as high as 1012 Fg(-1) and 750 Fg(-1) measured from CV and discharge curves, respectively. Compared with the theoretical specific capacitance of NiO 2573 Fg(-1), the degree of electrochemical utilization is 97% for NiO in the synthesized NiO/C composite. The superior electrochemical performance is attributed to the hierarchically porous structure of the synthesized NiO/C, its with a high specific surface area as well as a wide pore size distribution. Considering the excellent performance and facile preparation, this NiO/C composite should have great potential for application in energy storage and conversion devices. (C) 2013 Elsevier Ltd. All rights reserved.