Pt/C electrocatalysts were prepared from a solution of H2PtCl6 in ethylene glycol in the presence of XC-72 carbon by adding a small amount of sodium acetate as stabilizer. Repeated TEM images showed that the platinum nanoparticles were small and uniform in size and highly dispersed on XC-72 carbon supports when a small amount of sodium acetate solution was added to the synthesis solution. The Pt/C electrocatalysts exhibited very high electrocatalytic activity for liquid methanol oxidation. The effects of adding acetate on Pt particle size and size distribution are discussed. It is demonstrated that acetate can be used as a good stabilizer for preparing Pt/C catalyst with fine and uniform Pt particles.