Provided is a method of producing a membrane and electrode assembly (MEA) comprising: mixing a metal catalyst with pure water, perfluorinated polymer ionomer and a polar organic solvent to prepare a composition for forming a catalyst layer; coating a diffusion layer formed on an electrode support with the catalyst layer forming composition, drying to forming a catalyst layer, thereby preparing a cathode and an anode, respectively; and interposing an electrolyte membrane between the anode and the cathode. The electrode catalyst for a fuel cell is inactivated to prevent spontaneous oxidation, thereby stabilizing the catalyst.