Four DAD type co-oligomers have been synthesized by Stille condensation between monostannyl derivatives of furan/thiophene/selenophene/3,4-ethylenedioxythiophene (EDOT) and 4,7-dibromo-benzo[1,2,5]oxadiazole. All these co-oligomers were successfully electrochemically polymerized in dichloromethane and characterized by spectroelectrochemistry. All four polymers possess narrow optical band gap. Spectroelectrochemical studies of polymer films on indium tin oxide revealed that the replacement of donor EDOT with furan/thiophene/selenophene has affected the low-energy charge-carrier (bipolaron) formation significantly. Kinetic studies based on chronoamperometry show that the polymer P5 (EDOT-capped benzo[1,2,5]oxadiazole system) possess better electrochromic property with high transmittance (66%) in visible region than the other copolymers. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012