Catalyst impact on membrane life was examined using inductively coupled plasma spectroscopy, hydrogen peroxide soak, and open-circuit decay. The catalysts PtFe/C and PtNi/C were found to leach similar to 2 x less platinum than Pt/C. Nafion in hydrogen peroxide with Ni2+ emitted similar to 100 x less fluoride than with Fe2+. At open circuit, Nafion 111 was found to fail at similar to 115, 315, and 520 h with PtFe/C, Pt/C, and PtNi/C cathodes, respectively, at 90 degrees C. It is hypothesized that if the leached cation does not directly impact the membrane decay, e. g., a "poor Fenton reagent," then other cations such as dissolved platinum ions may become critical. (c) 2008 The Electrochemical Society.