This paper introduces a unique Method for achieving high dispersion of precious Metal nanoparticles on carbon nanotube Supports for electrocatalysts: the Surface thiolation of multiwall carbon nanotubes (MWNT). The high dispersion of Pt nanoparticles [i.e., small average particle size (1.5 nm) and narrow size distribution] was obtained by the surface thiolation of MWNT as supports, despite a considerably large Pt load (40 wt% Pt to MWNT) and the Use of MWNT with a relatively small surface area as supports to common activated carbon. In particular, EXAFS and XPS data revealed that the interaction between Pt nanoparticles and surface thiol groups Oil MWNT was the reason for the high dispersion. These highly dispersed Pt nanoparticles showed enhanced and stable electrocatalytic activity in Methanol oxidation and oxygen reduction reactions. This result indicates that the surface thiolation Of Supports is an effective way to obtain highly dispersed precious Metal nanoparticles to enhance electrocatalytic activity. (c) 2005 Elsevier Inc. All rights reserved.