Composites of poly(3,4-ethylenedioxythiophene) (PEDOT) and Ag particles were prepared by electrochemical polymerization of 3,4-ethylenedioxythiophene (EDOT) and the simultaneous electrochemical reduction of AgNO3 in the presence of poly(vinyl pyrrolidone) (PVP) as a stabilizer. The formation of Ag particles with PVP of various molecular weights and an electrochemical method was investigated. When the high PVP molecular weight was added to the Ag/PEDOT film, the average size of the Ag particles was high. Homogenous spherical Ag particles were observed when cyclic voltammetry was used in the reaction system, whereas chronoamperometry revealed aggregated Ag particles. UV-visible spectroscopy revealed the synchronized formation of Ag particles and PEDOT. The morphology and dispersion of the Ag particles in PEDOT were characterized by scanning electron microscopy. These results suggest that well dispersed homogenous Ag particles can be obtained by applying the proper electrochemical methods or by selecting the optimum PVP molecular weight.