This study investigates the effect of the anode diffusion layer on the cell performance and stability of a direct borohydride fuel cell (DBFC). Carbon paper with various PTFE contents and thicknesses is used as the anode diffusion layer. In the case of the DBFC, both hydrogen evolution and liquid fuel diffusion have to be considered while selecting an anode diffusion layer. Among the various PTFE-containing diffusion layers, the non-contained diffusion layer yields the best performance. Adding PTFE to the diffusion layer leads to improved gas transport but is unsuitable in the DBFC. In addition, the thinnest (100 mu m) diffusion layer gives the best performance among the diffusion layers with various thicknesses. The decrease in the length of the diffusion path is beneficial for both the release of hydrogen gas and the diffusion of liquid fuel. In addition, it is found that the hydrogen evolution rate increases with increasing cell performance. Overall, adequate diffusion of liquid fuel is more important for the performance of a DBFC than the release of hydrogen gas. (c) 2006 Elsevier B.V. All rights reserved.