A 28-W direct borohydride-hydrogen peroxide fuel-cell stack operating at 25 degrees C is reported for contemporary portable applications. The fuel cell operates with the peak power-density of ca. 50 mW cm(-2) at 1 V. This performance is superior to the anticipated power-density of 9 mW cm(-2) for a methanol-hydrogen peroxide fuel cell. Taking the fuel efficiency of the sodium borohydride-hydrogen peroxide fuel cell as 24.5%, its specific energy is ca. 2 kWh kg(-1). High power-densities can be achieved in the sodium borohydride system because of its ability to provide a high concentration of reactants to the fuel cell. (c) 2006 Elsevier B.V. All rights reserved.