Carbon nano-materials were applied to the gas diffusion layers of PEMFC. Gas diffusion layers consist of gas diffusion medium(carbon cloth or carbon paper) and micro-layers. Carbon blacks, such as Vulcan XC 72, have been widely used for the micro-layers. Main functions of gas diffusion layers are distribution of reactants to the active site of electrode, management of water supplied and/or generated and enhancement of electrical contact between the electrode and the bipolar plates. In this work, nano-fibers and nano-tubes are adopted to the micro-layer of gas diffusion layers. By applying nano-materials, thinner micro-layers can be fabricated. This newly made micro-layer showed higher gas permeability and good electric conductivity with similar degree of water management as well as enhanced performance. (c) 2005 Elsevier B.V. All rights reserved.