Copper doped zinc oxide thin film(Cu : ZnO) was deposited onmicroscopic glass substrate following a chemical technique called successive ion layer adsorption and reaction (SILAR). Structural characterization by X-ray diffraction (XRD) revealed loss of preferred c-axis orientation and decrease in particle size due to copper incorporation. Morphology using SEM shows porous polycrystalline structure. Optical band gap measurement using UVVIS spectrophotometer shows a decrease in band gap energy due to copper incorporation.Gas sensitivity in presence of 200 ppm(parts permillion) H2S was found to increase from ~40% for ZnO to ~60% for copper doped ZnO. Palladium surface sensitization was found to further enhance the sensitivity.