A study on the NO2 gas sorption ability of amorphous Ge33Se67 coated quartz crystal microbalance (QCM) is presented. The thin films have been characterized before and after sorption/desorption processes of NO2 by energy-dispersive X-ray spectroscopy (EDS), grazing angle X-ray diffraction (GAXRD), Raman spectroscopy, X-ray photoelectron spectroscopy (XPS) and atom force microscopy (AFM) measurements. These studies indicated that physisorption occurs when NO2 gas molecules are introduced into the chalcogenide film and the thin film composition or structure do not change. The mass loading due to NO2 gas sorption was calculated by the resonator's frequency shift. At the conditions of our experiment, up to 6.8 ng of the gas was sorbed into 200 nm thick Ge33Se67 film at 5000 ppm NO2 concentration. It has been established that the process of gas molecules sorption is reversible. (C) 2012 Elsevier B.V. All rights reserved.