Bismuth ferrite (BFO) and Ag substituted Bismuth ferrite with perovskite structure have been synthesized using sol-gel method and investigated for their gas sensing properties. Single phase and rhombohedral crystal structure of the samples were confirmed from XRD pattern. Oxidation state of the elements is confirmed using X-Ray Photoelectron Spectroscopy (XPS). Since Ag substituted Bismuth ferrite exhibited pronounced response to H2S gas as compared to other gases, H₂S gas sensing properties of Bismuth ferrite (BFO) and Ag substituted Bismuth ferrite were investigated in detail. Bi_0.9Ag_0.1FeO₃ (BAFO) exhibits enhanced sensitivity, quick response and selectivity towards H₂S as compared to BFO.