A novel monomer; 2-(3-nitrophenyl)-4,7-di(thiophen-2-yl)-1H-benzo [d]imidazole) (BIMN) was used for electrochemical copolymerization with 3,4-ethylenedioxythiophene (EDOT). Polymerization was achieved in acetonitrile (ACN)/dichloromethane (DCM) (1:1, 1:3 and 1:5, molar ratios) solution containing sodium perchlorate (NaClO 4 ) and lithium perchlorate (LiClO 4 ) mixture as the supporting electrolyte on an ITO electrode. The chemical structures of monomer and copolymers were characterized by nuclear magnetic resonance ( 1 H NMR) and scanning electron microscopy (SEM). The optical and electrochromic properties were investigated by UV-vis spectrophotometer and cyclic voltammetry, respectively. Combination of BIMN and EDOT provides lower oxidation potential, lower bandgap and higher optical contrast.