Sensing characteristics of tellurium-based thin films for 1 02 monitoring was studied systematically. The influence of contact materials, thermal treatment, temperature and thickness of the samples on the electrical conductivity and sensitivity to NO2 with respect to scanning electron microscopy analyses is given. The possibility is shown. to optimize the properties of the films for the development of a simple and stable NO2 sensor device with rapid response/recovery time and low operating temperature. The sensing mechanism is discussed for the direct interaction of gaseous species with lone-pair electrons of chalcogen atoms. (c) 2005 Elsevier B.V. All rights reserved.