Zr-doped ceria nanotubes (ZrxCe1-xO2) were obtained in a high yield from a hydrothermal reaction in an aqueous solution of NaOH with Ce(NO3)3 ·6H2O and ZrO 2 powder in a small proportion. The morphology and crystalline structure were characterized with X-ray diffraction, a scanning electron microscope, and a transmission electron microscope. Mechanisms for the growth of Zr-doped ceria nanotubes are proposed based on the Kirkendall effect; the formation of the tubular structure is strongly dependent on the precursor. This is the first report of a direct synthesis of cerium-oxide nanotubes in high yield. The surface area of the nanotubes is 76 m2/g and their average pore size is ̃52.2 nm. Catalytic measurements show that the nanotubes as synthesized are active for an oxygen-storage capacity and for ethanol reforming.