Electrochemical copolymerization of o-dihydroxybenzene (oDHB) and 3-methylthiophene (3MeT) was successfully achieved in boron trifluoride diethyl etherate by direct anodic oxidation of the monomer mixtures, although the oxidation potentials of oDHB and 3MeT were quite different. The influence of the applied polymerization potential on the synthesis of the copolymers was investigated. The higher applied potential favored the incorporation of 3MeT units into the copolymers. The structure and properties of the copolymers were investigated with UV-vis spectroscopy, fluorescence spectroscopy, FTIR spectroscopy, and thermal analysis. The novel copolymers had many advantages, including good redox activity, good thermal stability, and high electrical conductivity. Additionally, the copolymers fluorescence properties that were tunable through changes in the feed ratio of the monomer mixtures. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 115: 3273-3281, 2010