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 N2 adsorption/desorption. The X-ray diffraction and Raman scattering investigations of the freshly prepared sample confirmed the formation of β-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 10nm in diam) with length of 500–2000nm and ∼20nm thick. NiO/C composite possesses high specific surface area of 137m2 g−1 and a micro–meso–macroporous structure with a distribution of the pore size from 1 to 200nm. 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 1012Fg−1 and 750Fg−1 measured from CV and discharge curves, respectively. Compared with the theoretical specific capacitance of NiO 2573Fg−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.