Mesoporous nanowall cobalt oxide (Co(3)O(4)) thin films were prepared by a liquid crystal templated electrodeposition method. The as-prepared Co(3)O(4) thin films exhibited a highly porous nanowall structure composed of many interconnected nanoflakes with a thickness of 10-25 nm. The nanoflakes showed continuous mesopores ranging from 4 to 15 nm and formed a net-like structure leaving pores of 20-250 nm. The electrochromic performances of the Co(3)O(4) thin films were characterized by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The Co(3)O(4) thin film annealed at lower temperature exhibited better electrochromic performance. The film annealed at 200 degrees C exhibited a transmittance modulation of 40% at 633 nm with a coloration efficiency of 31 cm(2) C(-1), and fast response times with 2.5 s for coloration and 2s for bleaching. The high porosity and big surface area were responsible for the enhanced electrochromic properties. (C) 2010 Elsevier B.V. All rights reserved.