The electrically conductive composite films based on poly(3,4-ethylenedioxythiophene) (PEDOT) were synthesized. The PEDOT/silicate composite was prepared by the in-situ oxidative polymerization of EDOT monomer using ferric toluene sulfonate (FTS) oxidant in which tetraethylorthosilicate was added to form inorganic silicate network by sol-gel transformation. The PEDOT-gold composite film was also prepared by the in-situ redox reaction between PEDOT in neutral state and AuCl 3 . The neutral PEDOT was oxidized by AuCl 3 while AuCl 3 was reduced to form Au metal. These PEDOT based composite films were repeatedly oxidized and reduced and the electrochemical and thermal stability was monitored by cyclic voltammetry. PEDOT-gold film exhibited highly enhanced electrochemical as well as thermal stability compared to PEDOT-PSS and PEDOT-silicate films.