Poly3-[4-(4-pentyl-cyclohexyl)-phenyl]-thiophene(P3PhChPeT) films have been electrochemically synthesized by direct oxidation of 3PhChPeT in the mixed electrolyte of boron thrifluoride diethyl etherate(BFEE) and ethyl ether(EE) (4：1

by volume)．The oxidation potential of the monomer was measured to be 1．1 V (veisus Ag/AgCl)．P3PhChPeT in dedoped state is soluble in usual organic solvents such as tetrahydrofuran and chloroform

etc The structure of the polymer films was studied by infrared

Raman and UV-visible spectroscopies．The molar mass of the polymer was measured to be about 3400 g/mol with polydispersity of 1.23．The fluorescent spectra showed a single broad band at 565 nm with excitation at 450 nm．The thermal analysis result indicated that this polymer had a high thermal stability with a decomposition temperature higher than 500℃．