In this contribution, synthesis and characterization of a novel donor acceptor donor type bis(thiophene)-(4,4'-dinonyl-2,2'-bithiazole) comonomer (TNBTT) were performed and the electrochemical characterization of redox properties and electrochemical impedance spectroscopy studies of its polymer on carbon fiber microelectrode (CFME) were reported. The comonomer oxidation onto bare carbon fiber microelectrode starts (E-onset of the TNBTT) at 1.1 V vs. Ag/AgCl. Cyclic voltammetry of the polymer in monomer free electrolyte solution exhibits a well-defined oxidation and reduction peaks, and a linear increase in current densities was monitored. PTNBTT film shows the stability to overoxidation without any electroactivity loss up to + 1. 6 V vs. Ag/AgCl. Electrochemical impedance studies were performed on CFME/PTNBTT/electrolyte system. An equivalent electrical circuit for this composition was proposed and experimental data were simulated to obtain numerical values of the circuit components. Field emission scanning electron microscopy (FE-SEM) measurements were confirmed that the polymer film was deposited very well onto the surface of the carbon fiber microelectrode. (c) 2007 Elsevier B.N. All rights reserved.