By chemical reaction of CeCl3 and NaOH on carbon nanotube solution and subsequent heat treatment, ceria nanoparticles supported on carbon nanotubes were prepared. The processing parameters affecting the size of ceria particles were discussed. The particles were characterized by XRD and TEM. XRD patterns revealed that the particles exhibited CaF2-type crystal structure. The TEM micrograph showed that the mean sizes of ceria particles were about 6 nm.