Thiophene capped polystyrenes (TCP1, TCP2) were synthesized by atom transfer radical polymerization of styrene followed by Suzuki condensation with 2-thiophene boronic acid. Electrically conducting graft polymers of TCP1 and TCP2 with thiophene were achieved by electrochemical methods. Characterization of the graft polymers were performed by cyclic voltammetry (CV), Fourier transform infrared spectroscopy, differential scanning calorimetry, scanning electron microscopy analyses. Electrochromic properties of the conducting copolymers were investigated by spectroelectrochemistry, kinetic and colorimetry studies. The observed lambda(max) and band gap values were found to be at 432 nm, 2.10 eV and 453 nm, 2.13 eV for P(TCP1 -co-Th) and P(TCP2-co-Th), respectively. Also, we successfully established the utilization of dual-type complementary colored polymer electrochromic devices using P(TCP I co-Th)/poly(3,4-ethylenedioxythiophene) (PEDOT) in sandwich configuration. The switching ability, stability and optical memory of the electrochromic device were investigated with UV-Vis spectrophotometer and CV. P(TCP1-co-Th)/PEDOT switches between blue and brown. (c) 2005 Elsevier B.V. All rights reserved.