Pt catalysts for methanol electro-oxidation were prepared by thermal decomposition of platinum carbonyls. [Pt3(CO)6]n2- were synthesized from inorganic platinum compounds (PtCl4 or (NH4)2PtCl4) in H2O-MeOH solutions using carbon monoxide as a reducing agent. The progress of the platinum carbonyls synthesis reaction and its performance were monitored using UV-Vis spectroscopy. The obtained results clearly indicate the possibility of using platinum carbonyls as intermediates for the synthesis of pure and finely divided platinum particles. The electrochemical tests of the platinum powders performed in the polymer-electrolyte low-temperature methanol fuel cells (DMFC) indicated good electrocatalytic properties of these materials.