The undoped and 1.0–5.0 mol% La–doped In₂O₃hollow microspheres have been successfully synthesized via a simple hydrothermal method without template and gas sensor have been fabricated basing on them. The nanostructures and morphologies of the maintained hollow spheres were characterized by various experimental techniques. The gas sensing properties of these hollow microspheres were investigated systematically. The results indicated that among all the samples (pure, 1.0, 3.0 and 5.0 mol% La–doped In2O3), 3.0 mol% La–doped In₂O₃exhibited the highest response toward 10 ppm hydrogen sulfide (H2S) at 200 °C, having a response value of 17.8, approximately 4.8 times higher than pure In₂O₃. Furthermore, excellent selectivity, good repeatability and outstanding long-term stability were also achieved. The significantly enhanced sensing properties to H₂S could be attributed to the changes in distribution of different oxygen components, crystallite size and specific surface area caused by La doping.