This paper describes recent results of an investigation of the electrocatalytic oxidation of methanol at carbon-supported gold and goldplatinum nanoparticle catalysts. The exploration of the bimetallic composition on carbon black support is aimed at modifying the catalytic properties for methanol oxidation reaction (MOR) at the anode in methanol oxidation fuel cells. Gold and gold-platinum nanoparticles of 23 nm core sizes with organic monolayer encapsulation were prepared by two-phase protocol. The nanoparticles were assembled on carbon black materials and thermally treated. The electrocatalytic MOR activities were characterized using voltammetric techniques, and were compared with commercial catalysts under several conditions. The results have revealed some initial insights into the catalytic activity of gold-platinum nanoparticle catalysts. Implications of our findings to the design and manipulation of highly-active gold-platinum nanoparticle catalysts for fuel cell applications are also discussed. (c) 2004 Elsevier B.V. All rights reserved.