Requirements for purification of biohydrogen should be justified for practical power generation from proton exchange membrane fuel cells (PEMFCs) and a new design of composite structure consisted of microporous layers (MPLs) combined with catalyst layers (CLs) on individual carbon fiber of carbon textile electrodes is proposed to render much higher tolerance for the purified biohydrogen. The multilayer MPL/CL composite electrode was prepared by formation of microporous layers of Vulcan XC-72 carbon black and subsequent deposition of catalyst layers of Pt/C nanoparticles by electrophoretic deposition (EPD) process. Both the microstructural analysis and electrochemical reaction via both half-cell and single-cell testing system for the membrane electrode assemblies with such composite structure were conducted under FE-SEM and cyclic voltammetry to investigate the interaction between catalysts and biohydrogen at different purity levels and to evaluate the catalyst utilization efficiency as well. (C) 2008 Published by Elsevier Ltd on behalf of international Association for Hydrogen Energy.