We report an improved H₂S response of flexible gold (Au)–cobalt phthalocyanine (CoPc) heterojunction thin films at room temperature. The Au–CoPc films exhibit very high charge carrier density at the surface due to (i) the difference in work function of Au and CoPc and (ii) enhanced adsorbed oxygen on the CoPc surface owing to spillover effect. Both of these effects make the Au–CoPc films more oxidative to the H₂S in comparison to pure CoPc films. The response of the films on exposure to H₂S is attributed to the shrinkage of the hole accumulation layer of CoPc due to electron transfer from adsorbed electron donor H₂S. The gas sensing characteristics of the films were found to be stable for the bending radius >20 mm.