A series of polydimethylsiloxane (PDMS)/polythiophene (Pth)/carbon fiber (CF) composites was synthesized by electrochemical polymerization using tetrabutylammoniumtetrafluoroborate (TBAFB) as supporting electrolyte and acetonitrile as solvent. Composites were characterized by TGA, SEM, and mechanical tests and conductivity measurements. Conductivities of composites were in the range of 25 S/cm. SEM studies show that CF were coated by PDMS/Pth matrix and well oriented in the matrix. In mechanical tests it has been observed that higher percent elongation was obtained by increasing PDMS content whereas tensile strength and modulus of composites increases with increasing CF content. (C) 2002 Elsevier Science B.V. All rights reserved.