Crack free Ag2S thin films were deposited on glass substrates by aerosol assisted chemical vapor deposition (AACVD) using [Ag(S2CN (C2H5)(2))(3)](2) (1) as a precursor. Thin films were deposited from solution of methanol at 400 degrees C and characterized by X-ray diffraction (XRD), UV-vis spectroscopy, scanning electron microscopy (SEM), and energy dispersive X-ray (EDX) analysis. SEM image of thin film showed well-defined and porous surface morphology with an average particle size of 0.3-0.5 mu m. Optical band gaps energy of 1.33 eV was estimated for Ag2S thin film, by extrapolating the linear part of the Tauc plot recorded at room temperature. The gas sensing characteristics of the novel gas sensors based on Ag2S were investigated for the detection carbon monoxide. The effect of operating temperature and change in gas concentration on the performance of carbon monoxide were investigated. The sensing mechanism of sensor was discussed. (C) 2012 Elsevier B. V. All rights reserved.