Abstract: A novel synthesis method based on homogeneous precipitation using cerium （Ⅳ） nitrate as the starting material was developed to prepare ultrafine cerium oxide particles．Properties of the obtained samples were characterized by XRD‚DSC／TGA‚TEM and BET area measurements．A structure of fluorite cubic phase of the prepared samples with a BET specific surface area of101m
2 ／g was obtained．XRD results show that the prepared particles are of a large lattice parameter‚which indicates that the particles are very small．Moreover‚the DSC／TGA measurement results show that the weight loss of the particles is about 16．84％‚manifesting that the molecularformula of cerium oxide compound is CeO 2 ·2H 2 O．It is also indicated by TEM that the particles obtained by the
homogeneous precipitate method are  spherica- l like‚with an average particle size of about10nm．The sols obtained from CeO 2 particles are of the highest CeO 2 mass concentration of more than170g／L and are stable for more than four weeks without any precipitation．

Key words: nanosized particle, cerium oxide, structure characterization, homogeneous precipitation