Mixed oxide materials belonging to the perovskite family (ABO3, LaCoO3) have come under intense scrutiny for their possible applications in different scientific and technological fields, such as heterogeneous catalysis, oxygen sensors, solid oxide fuel cells and magnetic media. The growing interest in such mixed oxide systems relies on a detailed investigation of structure-properties relationships that can lead to the optimization of their performances with respect to different applications, e.g., catalysis, sensors, etc. Similar solid state devices would require high surface area thin films in order to optimize the full potential of these oxide materials; specifically, nanostructured systems with a high defect content (oxygen vacancies and local lattice disorder) are expected to show superior properties with respect to the conventional ones. The possibility to tailor these features as a function of the surface area and grain size appears thus as a powerful tool in order to optimize the material properties for functional applications. In particular the present investigation is focused on x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger electron spectroscopy (XE-AES) analysis of the main core levels (O 1s, Co 2p, Co LMM, La 3d, and La 4d) of LaCoO3 nanophasic powders obtained by combustion synthesis. The formation of LaCoO3 was ascertained by the position and shape of La 3d and Co 2p photopeaks. © 2001 American Vacuum Society.