Tungsten oxide (WO 3 ) thin films have been deposited on silicon(100) and alumina substrates by using a pulsed excimer laser deposition method in oxygen gas. The crystalline structure and crystallographic orientation of the WO 3 films, measured by glancing-angle X-ray diffraction (GXRD) system, suggested that there were distinct peaks of crystalline WO 3 (001), (111), (201), (121), (002), (112), and (022) on the film prepared at P O 2 =10Pa. The maximum sensitivity of WO 3 film, synthesized at P O 2 =10Pa for 200ppm NO x was increased with increasing substrate temperature. The maximum sensitivity for 200ppm NO and 200ppm NO 2 were approximately 65 and 170, respectively, at the operating temperature of 400 o C. The substrate temperature results in a notable change in NO x gas sensing properties of WO 3 thin films.