CuxNi1-xO electrochromic thin films were prepared by sol-gel dip coating and characterized by XRD, UV-vis absorption and electrochromic test. XRD results show that the structure of the Cu-x Ni1-xO thin films is still in cubic NiO structure. UV-vis absorption spectra show that the absorption edges of the CuxNi1-xO films can be tuned front 335 nm (x = 0) to 550 nm (x = 0.3). and the transmittance of the colored films decrease as the content of Cu increases. CuxNi1-xO films show good electrochromic behavior, both the coloring and bleaching time for a Cu0.2Ni0.8O film were less than 1 s, with a variation of transmittance up to 75%, at the wavelength of 632.8 nm. (c) 2005 Elsevier Ltd. All rights reserved.