Nanofibers of natural cotton cellulose with a degree of polymerization above 10,000 were prepared by electrospinning; they were then functionalized with a rare-earth nano-oxide material of cerium dioxide (CeO2) by means of the hydrothermal method to obtain the designated properties. The morphology, structure, and properties of the as-obtained nanocomposite fibers were characterized by scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, Fourier transform infrared spectroscopy, and ultraviolet (UV)-visible spectrophotometry. The results show that hydrothermally grown CeO2 nanoparticles exhibited a polycrystalline cubic fluorite structure and could be dispersed uniformly on the surface of the cellulose nanofiber. The strong interface and electrostatic interactions between the nanoparticles and nanofibers effectively prevented nanoparticle fall-off. The modified natural cotton cellulose nanofibers showed excellent protection against UV radiation because of the function of the CeO2 particles. Such cellulose nanocomposite materials could have potential applications in UV protection for data-storage or memory devices. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1524-1529, 2013