Electrochemical copolymerization of pyrrole and indole was performed galvanostatically in a solvent of acetonitrile (AN)/water (vol %: 99/1). The product obtained was characterized by cyclic voltammetry and infrared spectroscopy. The influence of the monomer feed ratio of pyrrole and indole on the synthesis of the copolymer was investigated. The amount of pyrrole units in the copolymer chain increased with increase of the concentration of the pyrrole monomer in the solution. The results showed that the electrochemical activity of the copolymer was improved as the incorporation of pyrrole units increased. Thermogravimetric analysis was carried out to investigate the properties of the copolymer.