Poly(3-[4-(4-pentyl-cyclohexyl)-phenyl]-thiophene) (PPeChPhT) and poly(3-[2-fluoro-4-(4-pentyl-cyclohexyl)-phenyl]-thiophene) (PFPeChPhT) films were electrosynthesized by direct oxidation of the corresponding monomers in the mixed electrolytes of boron trifluoride diethyl etherate and ethyl ether (4:1, by volume). As grown PPeChPhT and PFPeChPhT films are in doped states and have conductivities of 0.10 and 0.11 S cm(-1), respectively. These two polymers in dedoped states are soluble in usual organic solvents such as tetrahydrofuran and chloroform, etc. The molar masses of the polymers were measured to be about 3400 g with dispersity of 1.32 (PPeChPhT) and 9300 g and dispersity of 1.51 (PFPeChPhT). Fluorescent spectral results showed that the polymers were strong yellow-green light emitters. Thermal degradation analysis results indicated that these polymers had high thermal stability with decomposition temperatures of about 500 degrees C. (c) 2005 Elsevier B.V. All rights reserved.