Electrochemical copolymerization of furan and 3-methyl thiophene was performed potentiostatically in a binary solvent system consisting of boron trifluoride-ethyl ether and additional ethyl ether ( mole ratio 2: 1). The product obtained was characterized by cyclic voltammetry and infrared spectroscopy. The influence of polymerization potential on the synthesis of the copolymer was investigated. The lower potential favored the incorporation of furan units into the copolymer. The conductivities of synthesized homopolymers and copolymers were determined by the four-probe technique. Thermogravimetric analysis (TGA) was also carried out to investigate the properties of the copolymer. (C) 2004 Kluwer Academic Publishers.