In this work, the effects of sodium borohydride concentration on the performance of direct borohydride fuel cell, which consisted of Pd/C anode, Pt/C cathode and Na(+) form Nafion (R) membrane as the electrolyte, have been investigated in steady state/steady-flow and uniform state/uniform-flow systems. The experimental results have revealed that the power density increased as the sodium borohydride concentration increased in the SSSF system. Peak power densities of 7.1, 10.1 and 11.7 MW cm(-2) have been obtained at 0.5, 1 and 1.5 M. respectively. However, the performance has decreased when the sodium borohydride concentration has been increased. and the fuel utilization ratios of 29.8%, 21.6% and 20.4% have been obtained at 0.5, 1 and 1.5 M, respectively in the USUF system. (C) 2009 Elsevier B.V. All rights reserved.