In this study, a proton-exchange membrane for fuel cells was prepared via a two-step reaction with an allyl methacrylate (AMA) as an asymmetric crosslinking agent. First, a linear-chain polymer was synthesized, consisting of hydrophilic 2-acrylamido-2-methylpropane-sulfonic acid (AMPS), hydrophobic 2,2,2-trifluoroethyl methacrylate (TFEMA), and AMA. Subsequently, we crosslinked the linear-chain polymer by reacting the remaining allyl group during dry heating. The proton conductivity of the prepared membrane was 7 x 10(-2) S/cm at room temperature. The membrane was characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry, and atomic force microscopy. The polymer electrolyte membrane fuel cell (PEMFC) performance was evaluated for a membrane electrode assembly composed of the crosslinked AMPS-TFEMA-AMA/fluoroalkyl graft polymer (FGP) membrane. As a result of a power-generation test, a maximum power density of 174 mW/cm(2) at a current density of 400 mA/cm(2) was observed for a PEMFC single cell. Consequently, it was confirmed that the AMPS-TFEMA-AMA/FGP membrane for PEMFC could easily be prepared via a two-step reaction at a low cost and that PEMFC exhibited a cell performance and that of cells with the Nafion membrane. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 3343-3350, 2009