BulkZrO2 and SnO2 powders were separately synthesized by disc type ultrasonicated microwave assisted followed centrifuge technique. Synthesized powders of bulk SnO2 and ZrO2 are not exactly stoichiometric and hence not insulating. Nanocomposite material, Zr(0.25)Sn(0.75)O4was prepared by using synthesized ZrO2 and SnO2 powders by taking their 1:3 proportion. Thick films of nanostructured pure Zr(0.25)Sn(0.75)O4 powder were fabricated by screen printing technique. These films were surface activated by dipping technique using bismuth oxide (Bi2O3) for different intervals of time, viz. 5 min, 15 min, 30 min and 45 min followed by firing at 450oC for 30 min. It was observed that, the 15 min Bi2O3 activated Zr(0.25)Sn(0.75)O4 thick film is most sensitive to 5 ppm H2S gas at room temperature.The average crystallite size was observed to be of 8.1 nm and determined using Scherer?s formula. Characterization techniques such as X-Ray diffraction studies (XRD), Field effect scanning electron microscopy (FESEM), Energy dispersive analysis (EDAX) by X rays, etc. were employed to study the average particle size, surface morphology and elemental analysis of the nanocomposite. The gas response, selectivity, response and recovery times of the sensor in the presence of H2S and other gases were studied and discussed.