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 10–25nm. The nanoflakes showed continuous mesopores ranging from 4 to 15nm and formed a net-like structure leaving pores of 20–250nm. 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°C exhibited a transmittance modulation of 40% at 633nm with a coloration efficiency of 31cm 2 C −1 , and fast response times with 2.5s for coloration and 2s for bleaching. The high porosity and big surface area were responsible for the enhanced electrochromic properties.