The electrochemical behavior of the novel fuel cell directly using aqueous ammonia borane (NH3BH3) as the fuel has been systematically investigated. The cell consists of an oxygen cathode and an ammonia borane solution fed anode, where the catalyst layers are made of Vulcan XC-72 with 46.6wt.% Pt. An anion exchange membrane is employed as the electrolyte. It is found that the concentrations of NH3BH3 solution and temperatures significantly affect the open circuit potentials of the anode as well as the cell performance. Although the cell voltages decrease with the increase of current densities, the cell is capable of discharging at a current density of 185 mA cm(-2) with the cell potential larger than 0.6V. The obtained high energy densities indicate that the direct ammonia borane fuel cell holds potential applications for portable devices. (c) 2008 Elsevier B.V. All rights reserved.