CdS and copper doped CdS thin film were synthesized by CBD method and characterized using XRD, EDAX, FESEM, TEM and UV-Vis spectrophotometer. Structural characterization reveals presence of cubic phase. EDAX analysis shows nearly stoichiometric films with presence of Cu in few amounts. The particle size of CdS (similar to 16-26 nm) decreased with copper doping. The bandgap decreased from 2.54 eV to 2.47 eV with increase in copper incorporation. Reflectance and transmittance measurements were studied to get information about optical property. The electrical conductivity and dielectric property were investigated using impedance spectroscopy. Semiconducting metal oxides (SMO) commonly employed in gas sensors requires high operating temperatures. Metal sulphide thin films can be a potential sensing material for new age low temperature gas sensors. An enhancement is sensitivity was observed due to incorporation of copper in CdS and a significantly high sensitivity of similar to 57% for copper doped CdS was exhibited at a reasonably low temperature of 150 degrees C in presence of 200 ppm LPG. (C) 2016 Elsevier B.V. All rights reserved.