The nanocrystalline La1-xBaxFeO3 powders with x <= 0.3 were prepared by a sol-gel method. X-ray diffraction patterns indicate that the nanocrystalline La1-xBaxFeO3 powders are perovskite phase with orthorhombic structure. With the increasing concentration of elemental barium, the growth of the grain size is restrained. In addition, the resistance and ethanol gas-sensing properties of La1-xBaxFeO3 based sensors strongly depend on the Ba concentration. The highest response to ethanol gas (500 ppm) is 172 at 240 degrees C for the La1-xBaxFeO3 based sensor with x=0.25. (C) 2010 Elsevier B.V. All rights reserved.