Nanocrystalline alumina (Al2O3) powder has been synthesized by the d.c. arc plasma method at atmospheric conditions using aluminium electrodes. Structural characterization by X-ray diffraction and transmission electron microscopy confirmed the ultrafine nature of the particulates. Investigation of the size distribution revealed a long-normal behaviour of the nanoparticles. Chemical analysis of the particulates was carried out using X-ray photoemission spectroscopy. The Al 2p core level spectrum revealed the presence of unreacted Al0, in addition to Al3+, suggesting a core of Al0 surrounded by a layer of Al2O3 as the particle structure.