Thick films of pure and various concentrations of La1−xSrxCoO3 (x = 0.0, 0.1, 0.2, 0.3 & 0.4) were prepared by solgel technique. Morphological and structural properties of the samples were obtained using the scanning electron microscopy (SEM) and X-ray diffraction techniques respectively. The H2S gas sensing properties of these thick films were investigated at different operating temperatures and H2S gas concentrations. The surface resistance of thick films decreases when exposed to H2S gas. The La1−xSrxCoO3 based sensor with x = 0.3 shows better sensitivity towards H2S gas at an operating temperature 210oC. The effect of Sr doping on sensitivity, response time and recovery time of the sensor in the presence of H2S and other reducing gases were studied and discussed.