Tungsten oxide (WO3) thin films have been deposited on silicon(1 0 0) and alumina substrates by using a pulsed excimer laser deposition method in oxygen gas. The crystalline structure and crystallographic orientation of the WO3 films, measured by glancing-angle X-ray diffraction (GXRD) system, suggested that there were distinct peaks of crystalline WO3(0 0 1), (1 1 1), (2 0 1), (12 1), (0 0 2), (1 12), and (0 2 2) on the film prepared at P-O2 = 10 Pa. The maximum sensitivity of WO3 film, synthesized at P-O2 = 10 Pa for 200 ppm NOx was increased with increasing substrate temperature. The maximum sensitivity for 200 ppm NO and 200 ppm NO2, were approximately 65 and 170, respectively, at the operating temperature of 400 degreesC. The substrate temperature results in a notable change in NOx gas sensing properties of WO3 thin films. (C) 2002 Elsevier Science B.V. All rights reserved.