To get nanostructured nickel oxide (NiO) at low cost, a template-free approach (electrospinning combined with direct annealing) has been developed to prepare NiO nanofibers. The obtained NiO nanofibers not only exhibit higher stability even at high temperature (400 degrees C), but also show a typical pseudocapacitive capacitance. It has been found that the value of the specific gradually decreases with the discharge current density and a highest specific capacitance of 227.5 F/g can be achieved at a constant current density of 1 A/g in 1 M KOH electrolyte.