SnO2 nanopowders were prepared by sol-gel method. The longer is an operating time or a storage period time, the lower is the air resistance (RO) of the sensor. To investigate the stability of the sensing material, the examine methods of C-ray diffraction (XRD) and transmission electronic microscope (TEM) and flour transmission infrared (IR) were selected to examine fresh powders (freshly prepared) and old powders (stored for 90 and longer than 200 days). The adsorption oxygen species reducing was one of the factors infecting the long-term stability of the sensor based on tin dioxide. And the addition of BaTiO3 modified FT-IR spectra of the samples and improved the stability of the sensing material. (C) 2004 Elsevier B.V. All rights reserved.