A fabrication method of membrane electrode assemblies (MEAs) for polymer electrolyte fuel cells (PEFCs) using a thin preformed precursor sheet has been described. A preformed precursor sheet was sandwiched between two gas-diffusion electrodes, and the resulting precursor electrode assembly is hot pressed at 150 degrees C for 2 min. Due to thermoplastic property of the precursor sheet, the catalyst layer of the gas-diffusion electrode may be embedded into the preformed precursor sheet and more effective three-phase boundaries are formed. The MEAs prepared by the present method give, in single-cell tests at 75 degrees C, current density of 0.4 A cm(-2) at 0.5 V. (C) 2004 The Electrochemical Society.