This study employed fuel cell gas diffusion layers (GDLs) consisting of carbon fiber paper made from carbon fiber felt with different yard weights in proton exchange membrane fuel cells (PEMFCs), and investigated the relationship between the yard weight of the carbon fiber paper and the fuel cell performance and thickness of the gasket. In this paper we discuss the relationship between carbon fiber felt with different yard weights and fuel cell performance and also explore the effect of carbon fiber paper thickness, air permeability, surface resistivity, and structural study. We focused on the material used for the gas diffusion layer in this study. Carbon fiber paper made in-house in this study contained 10 wt% (all percentages are by weight unless otherwise noted) phenolic resin. When the tested area was 25 cm(2), the test temperature was 40 degrees C, the gasket thickness was 0.06 mm, and the yard weight 70 g m(-2), fuel cell current density was 1968 mA cm(-2) at a load 0.3 V. When the gasket thickness was 0.36 mm. and yard weight was 190 g m(-2), fuel current density was 17 10 mA cm(-2) at a load of 0.3 V. (C) 2008 Elsevier B.V. All rights reserved.