Nanometer perovskite-type oxides La1-xSrxMO3-delta (M = CO, Mn; x = 0, 0.4) have been prepared using the citric acid complexing-hydrothermal-coupled method and characterized by means of techniques, such as X-ray diffraction (XRD), BET, high-resolution scanning electron microscopy (HRSEM), X-ray photoelectron spectroscopy (XPS), temperature-programmed desorption (TPD), and temperature-programmed reduction (TPR). The catalytic performance of these nanoperovskites in the combustion of ethylacetate (EA) has also been evaluated. The XRD results indicate that all the samples possessed single-phase rhombohedral crystal structures. The surface areas of these nanomaterials ranged from 20 to 33 m(2) g(-1), the achievement of such high surface areas are due to the uniform morphology with the typical particle size of 40-80 nm (as can be clearly seen in their HRSEM images) that were derived with the citric acid complexing-hydrothermally coupled strategy. The XPS results demonstrate the presence of Mn4+ and Mn3+ in La1-xSrxMO3-delta and Co3+ and Co2+ in La1-xSrxMO3-delta, Sr substitution induced the rises in Mn4+ and Co3+ concentrations; adsorbed oxygen species (O-, O-2(-), or O-2(2-)) were detected on the catalyst surfaces. The 02-TPD profiles indicate that Sr doping increased desorption of the adsorbed oxygen and lattice oxygen species at low temperatures. The H-2-TPR results reveal that the nanoperovskite catalysts could be reduced at much lower temperatures (<240 degrees C) after Sr doping. It is observed that under the conditions of EA concentration = 1000 ppm, EA/oxygen molar ratio = 1/400, and space velocity = 20,000 h(-1), the catalytic activity (as reflected by the temperature (T-100%) for EA complete conversion) increased in the order of LaCoO2.91 (T-100% = 230 degrees C) approximate to LaMnO3.12 (T-100% = 235 degrees C < La0.6Sr0.4MnO3.02 (T-100% = 190 degrees C < La0.6Sr0.4CoO2.78 (T-100% = 175 degrees C); furthermore, there were no formation of partially oxidized by-products over these catalysts. Based on the above results, we conclude that the excellent catalytic performance is associated with the high surface areas, good redox properties (derived from higher Mn4+/Mn3+ and CO3+/ CO2+ ratios), and rich lattice defects of the nanostructured La1-xSrxMO3-delta materials. (C) 2007 Elsevier B.V. All rights reserved.