Nickel oxide thin films were deposited on SnO2:F-coated glass using pulsed laser deposition. The influence of the oxygen pressure and the substrate temperature on the structure, morphology and electrochromic performances of NiOx thin films were investigated. Whatever the oxygen pressure (Po-2 less than or equal to 10(-1) mbar) and substrate temperature (RT less than or equal to T-s less than or equal to 300 degreesC) NiOx films were crystallized and exhibited a non-stoichiometry (x < 1), which increased (i.e. x decreased) with decreasing oxygen pressure. At an optimum oxygen pressure of IF 1 mbar and low substrate temperature, the reversible color/bleaching process was mainly associated to the Ni3+/Ni2+ redox process, The appearance of a broad signal in the cyclic voltammograms (CVs) of films deposited at higher substrate temperature suggested the existence of surface reactions in agreement with film densification. (C) 2002 Elsevier Science B.V. All rights reserved.