In this study, we employed carbon nanotubes (CNTs)-modified polyaniline (PANI-CNTs) electrochromic (EC) thin film as the anodically coloring electrode and CNTs-modified poly(3,4-ethylenedioxythiophene) (PEDOT-CNTs) EC thin film as the cathodically coloring electrode. The electrochemically deposited PANI-CNTs film shows a transmittance change (Delta T) of 41.4% and a coloration efficiency (eta) of 302 cm(2) C-1 at 700 nm. The PANI-CNIs film was assembled in a complementary electrochromic device (ECD) with the PEDOT-CNTs film, which exhibits a Delta T of 58.5% and a coloration efficiency of 562 cm(2) C-1 at 630 nm. The CNTs-modified ECD achieved a high eta value of 836 cm(2) C-1 at 650 nm and maintained a Delta T value of 35%, as compared to an eta value of 285 cm(2) C-1 and a similar Delta T value (35%) at 570 nm for a complementary PANI-PEDOT ECD without employing CNTs on both electrodes. No decay was noticed in both coloration efficiency and transmittance change after switching for 500 cycles. (C) 2011 Elsevier B.V. All rights reserved.