Poly(1,4-bis(2-thienyl)-benzene) (PBTB) is electrochemically synthesized on ZnO-coated electrode to form PBTB/ZnO nanocomposite electrochromic film. The composite film exhibits a noticeable electrochromism with reversible color changes from yellow (neutral state) to green (oxidized state). From SEM images, PBTB/ZnO nanocomposite film presents the smooth and even surface, which is different from the morphology of the ZnO nanoridges with average width of about 50-100 nm. Spectroelectrochemical analysis reveals that the composite film has fast switching time of 0.9 s (2 s for pure PBTB film) at 1100 nm. Moreover, it can retain up 90% (50% for pure PBTB film) of its original electroactivity after 300 cycles stability measurement. All the results demonstrate that the electrochromic performances are significantly enhanced through incorporating PBTB with ZnO nanoridges. Accordingly, nanocomposite structure plays an essential role in improving electrochromic switching time and long-term stability of electrochromic materials due to shorter counterion diffusion distance and good adhesion to the electrode. (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.034302jes] All rights reserved.