The cell performance and the polarization behavior of the fuel cell using alkaline NaBH(4)-N(2)H(4) solutions as the fuel were investigated. It was found that the use of different membrane: anion exchange membrane (AEM) or cation exchange membrane (CEM) would influence the cell performance and cathode polarization behavior. The direct borohydride fuel cell (DBFC) using CEM gave a higher power density than that using AEM, but the direct hydrazine fuel cell (DHFC) using CEM gave a lower power density compared with the DHFC using AEM. In the DBFCs using CEM, N(2)H(4) addition in alkaline NaBH(4) solution improved the cell performance but it did not make any difference when adding more N(2)H(4). On the other hand, in the DBFCs using AEM, cell performance was improved with increasing the amount of N(2)H(4) in the anolyte. (C) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.