Polypyrrole (PPy) was synthesized by chemical oxidative polymerization technique using Ferric Chloride (FeCl 3 ) as an oxidant and Pyrrole as a monomer. The ratio of oxidant to monomer was 2.5:1. The polymerization was carried out at ~ 5 °C. The materials were characterized by using SEM, FTIR and XRD. The electrical conductivity was measured by two probe method and was found to be 1.389 × 10 -2 S/cm at room temperature. H 2 S gas sensor was fabricated by casting thin films of Polypyrrole on the

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... integrated electrodes, at room temperature. Sensing experiments were performed on these films with the injection of 10 ppm to 100 ppm level H 2 S at room temperature. The response and recovery time were obtained. It was found that, response time decreased from 64 sec to 13 sec as the concentration of H 2 S increased from 10 ppm to 100 ppm, while the recovery time increased from 192 sec to 644 sec. The possible response mechanism is discussed.