Boron- and nitrogen-containing porous carbon nanofibers (BN-CNFs) were prepared through one-step electrospinning using boric acid (H3BO3) and urea as boron and nitrogen precursors and a subsequent thermal treatment. The BN-CNFs showed higher capacitance and energy/power density values than the control sample of CNFs in aqueous electrolyte; the large surface area of 559 m(2) g(-1) and the NH, COOH, and [O]BN functional groups facilitated these improvements. The specific capacitance of the super-capacitor was 180 F g(-1) at 1 mA cm(-2), and the energy density was 17.2-23.5 W h kg(-1) in the power density range of 400-10,000 W kg(-1) in an aqueous electrolyte. (C) 2012 Elsevier B.V. All rights reserved.