We report a self-supported Co3O4 nanowire array film prepared by a facile thermal oxidative decomposition method and its fast electrochomic properties. The electrochromic performances of Co3O4 nanowire array film are investigated in 0.1 M KOH by means of transmittance, cyclic voltammetry (CV) and chronoamperometry (CA) measurements. The effective area of the Co3O4 nanowire array film is 2 x 2 cm(-2). The Co3O4 nanowire array film exhibits a transmittance modulation of 32% in the visible region and fast response times with 1.8 s for coloration and 1.4 s for bleaching. The electrochemical stability of the Co3O4 nanowire array him is characterized by chronoamperometry with potentiostatic cycling. After 4500 cycles, the peak Currents of the film maintain 88% of the highest values. (C) 2009 Elsevier B.V. All rights reserved.