This study concerns the electrochemical synthesis of homopolymer and bipolymer films of thiophene and furan by the use of tetraethylamonium tetrafloroborate (Et4NF4B) and tetrabuthylamonium hexafluorophosphate (Bu4NF6P) supporting electrolytes and the elucidation of their structures. The electrochemical behaviors of the polymers were investigated by the use of cyclic voltammetry (CV). The surface films of the samples were taken with scanning electron microscopy (SEM). The conductivity of the films synthesized was determined by the use of four-probe technique. The conductivity of the homo- and bipolymers were measured both from the solution and the electrode side. The lowest conductivity was the conductivity of the electrode side of PF prepared by the use of 0.2 M Et4NF4B (9.95 x 10(-6) S cm(-1)) and solution side of PF prepared by the use of 0.2 M Bu4NF6P (9.95 x 10(-6) S cm(-1)) in acetonitrile. The highest conductivity was obtained in the solution side of PT (8.66 x 10(-2) S cm(-1)) prepared by the use of 0.2 M Bu4NF6P in acetonitrile. To elucidate the structures of the homo- and bipolymers prepared their magnetic susceptibility values were determined by the use of Gouy balance. The conductivity of the polymers prepared was found to be of bipolaron type due to the fact that their magnetic susceptibility values were negative. Also the FTIR spectra of the polymers were taken and their thermogravimetric analysis were carried out. The maximum decomposition temperatures were 600 degreesC for PT and 310 degreesC for PT in Et4NF4B. The TGA data revealed that the thermal stability of the polymers prepared was quite high. The FTIR spectra of homopolymers and their 1:1 mechanical mixtures. are similar but there are significant shifts in their absorption bands. However the investigation of the IR bands does not give a definite idea whether the polymer is a copolymer of bilayer structure. The electrochemical behavior of the polymers was investigated by taking their multi-scan cyclic voltammograms. The examination of the CV data revealed that the electrochemical behaviors of the polymers synthesized by the use of different supporting electrolytes were different. The change of the covering order also changed the electrochemical properties. It was therefore conclude that the structures of the polymers obtained were different. This result was supported by TGA, magnetic susceptibility, SEM and conductivity data. (C) 2003 Elsevier B.V. All rights reserved.