NdFe1-xCoxO3(x=0.0-0.5)powders were prepared by a sol-gel citric method.X-ray diffraction was used to confirm the phase composition of the powders.All the samples are orthorhombic structure.The unit cell volume and grain size decreased with an increase of Co content x.The conduction type of the NdFe1-xCoxO3 perovskite oxides changed with the increasing Co content x.When x0.3.All the sensors presented higher responses and lower optimal operating temperatures.The highest response to 0.03% CO gas reached 1215% at 170 ℃ for NdFeO3 sensor; however,Co2+doping in NdFeO3 did not improve the gas responses.