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Different La 1-x Ba x MnO 3+δ nanopowders (with x = 0–0.20) were prepared using a traditional sol-gel method. Each sample had a size distribution between 50 and 80 nm with a single perovskite-type structure. The La 1-x Ba x MnO 3+δ based sensors showed excellent gas-sensing performance toward acetone (25–500 ppm) at 300 °C. It was also found that the La 0.80 Ba 0.20 MnO 3+δ sensor exhibited a fast response (≈25 s) and recovery time (≈15 s) in the presence of 100 ppm acetone gas, while the response value of the La 0.80 Ba 0.20 MnO 3+δ sensor to 500 ppm acetone reached 1350%. Moreover, these sensors also had good reproducibility and sensitivity to acetone. It reveals that Ba2+ as doping agent can partially convert Mn3+ to Mn4+, introducing numerous hole carriers into the p-type LaMnO 3+δ semiconductor and increasing the amount of chemisorbed oxygen ions on the surface, which can enhance the response of the sensor toward acetone. Moreover, this doping effect may also increase the hybridization of Mn 3d - O 2p orbits and double exchange interaction existing in the hybrid Mn3+/Mn4+ system, thereby promoting the carriers' conduction rate and gas sensing speed. These results suggest that the La 1-x Ba x MnO 3+δ perovskite-type structures can have large applicability in industrial acetone sensing. [ABSTRACT FROM AUTHOR]