Conducting polythiophene films hundreds of micrometers thick was first obtained by electrochemical polymerization of thiophene in freshly distilled BF3-diethyl ether solution at stainless steel electrode. The tensile strengths of these films were much higher than those of some widely used engineering plastics such as polypropylene and poly(vinyl acetate). These films can be easily cut by conventional mechanical methods into a variety of structures like a metallic sheet.