A new of soluble sulfonated conductive copolymer has been synthesized by electrochemical oxidation in the presence of anhydrous FSO3H. The sulphur-to-nitrogen ratios indicated that copolymers were formed in addition to the incorporation of SO3- groups into polymeric backbone. The sulfonated copolymer films have better solubility in DMSO and KOH. The conductivity of the copolymer films increases with the increase in the number of thiophene rings in the polymeric backbone. Copolymer films synthesized were investigated by cyclic voltammetry, UV-visible, FT-IR and H-1-NMR spectroscopy, dry conductivity and intrinsic viscosity measurements, elemental analysis and SEM pictures. (c) 2004 Elsevier Ltd. All rights reserved.