The authors report about preparation and characterization of thin films of MoO3 as a material for gas-sensing applications. Structural investigation of the films is carried out by electron microscopy and X-ray diffraction techniques. The sensing behavior of the MoO3 films was tested to NO2, showing capability to detect a few ppm of NO2 with considerably short response time. (C) 1998 Elsevier Science S.A. All rights reserved.