This study was primarily focused on the preparation and characterization of conducting polymer/metal nanocomposites. Poly(3,4-ethylenedithiathiophene) was prepared onto ITO electrodes as thin film shapes by electrochemical polymerization and reduced with constant potential. When the polymer films were doped with K2PtCl6 solution, they were easily get oxidized due to the concurrent reduction of Pt(IV) to Pt(0). This procedure ended up with the formation of polymer/metal composites. In-situ spectroelectrochemistry was used to investigate the composite formation processes. The final composites were indentified with SEM and EDAX. Catalytic decomposition of methanol on these composite electrodes was observed by using cyclic voltammetry.