In this study bis (ethylcarbazole) diethylthiazole (ECzEBTECz) comonomer was synthesized by Stille coupling reaction and then electrochemically polymerized. The redox behaviour of resulting polymer, P [ECzEBTECz] was investigated by cyclic voltammetry at different scan rates. Polymeric film was further characterized by ATR-FTIR, UV-Visible and fluorescence spectrophotometric measurements. The capacitive behaviour of polymer was investigated by electrochemical impedance spectroscopic (EIS) measurements. Electrical equivalent circuit was applied to the experimental data to correlate the results, obtain the parameter of each element and explain the interface between the glassy carbon/P[ECzEBTECz]/Bu4NPF6 system. Voltammetry results show that the redox behaviour of the polymeric film is quite reversible and stable even at high scan rates. Fluorescence measurements suggest that the emission of the bithiazole moiety allows access to full visible spectrum so the color of polymer expected to suit to the need of optical applications such as LED. (C) 2014 Elsevier Ltd. All rights reserved.