Cerium oxide nanoparticles (CeO2) have been synthesized through precipitation in aqueous medium at room temperature using cerium III nitrate hexahydrate (Ce(NO3)3·6H2O) as precursor and poly(vinylpyrrolidinone) (PVP) as surfactant. Scanning electron microscope (SEM) was used to evaluate cluster formation and Transmission electron microscopy (TEM) images were obtained in order to determine the shape, average size and uniformity of the nanoparticles. The elements presented (cerium and oxygen) in the nanoparticles were confirmed through energy-dispersive X-ray spectroscopy (EDS). X-ray diffraction (XRD) patterns indicated the formation of cerium oxide with cubic structure and lattice parameters of 5.41036 Å. Average crystallite size was found to be 5.47 nm and no other crystalline phase was detected.