It is the first report that the uniformly dispersed nickel oxide nanoparticles were synthesized on the substrates of multi-walled carbon nanotubes (MWNT) via electrochemical technique. The morphology and chemical state of the NiO(x)/MWNT composite were characterized using scanning electron microscopy and X-ray photoelectron spectroscopy. The electrochemical test results revealed that the surface-decorated composite with oxide particle sizes of 15-30 nm can deliver specific capacitance about 190 Fg(-1), tenfold greater than that of pure MWNT. Meanwhile, the electrode displayed excellent cycling stability with nearly 100% coulombic efficiency over 1000 cycles and good rate capability with acceptable specific capacitance fading, indicating that this novel nanostructured composite electrode was a promising candidate for electrochemical capacitors. (C) 2011 Elsevier B.V. All rights reserved.