A method of preparing carbon-loaded, gold-based nanoparticle catalysts useful as anode catalysts for the electrocatalytic methanol oxidation reaction (MOR) as well as the oxygen reduction reaction (ORR). Au.sub.mPt.sub.nM.sub.100-m-n catalysts may be prepared by either a two-phase protocol or by a thermal decomposition/reduction protocol. The prepared nanoparticles having different bimetallic ratios are assembled on carbon black support materials and activated by thermal treatment. This approach provides good control of nanoparticle size, composition and/or surface properties. Electrocatalytic MOR activities of the prepared and activated AuPt nanoparticle provided in accordance with the methods of the invention are present in both acidic and alkaline electrolytes.