Uniform CeO 2 nano-octahedrons and the strawlike CeO 2 nanostructures assembled by numerous thin nanotubes have been successfully synthesized by a facile one-step hydrothermal synthesis route only using Ce(NO 3 ) 3 Á6H 2 O as cerium resource, Na 3 PO 4 Á6H 2 O as mineralizer and no surfactant or template. The reaction time was systematically investigated. XRD, SEM, TEM, XPS, Raman scattering, Photoluminescence spectra and M-H curves were employed to characterize the samples. The results showed that both CeO 2 nano-octahedrons and nanotubes owned a fluorite cubic structure and the octahedrons-like structures gradually transform into nanotubes with the increase of the reaction time. The possible formation mechanism based on nucleation-dissolution-recrystallization of nanoparticles was proposed. It is found that there are Ce 3? ions and oxygen vacancies in surface of samples. All the samples exhibited similar emission peaks of room temperature photoluminescence and the emission intensity increases with the increase of concentration of oxygen vacancies. The M-H curves of CeO 2 nano-octahedrons and nanotubes exhibit excellent room-temperature ferromagnetism, which is likely attributed to the effects of the Ce 3? ions and oxygen vacancies.