Single- crystal cerium hydroxide carbonate ( Ce( OH) CO3) triangular microplates with the hexagonal phase have been successfully synthesized by a hydrothermal method at 150 degrees C using cerium nitrate ( Ce( NO3) center dot 6H(2)O) as the cerium source, aqueous carbamide as both an alkaline and carbon source, and cetyltrimethylammonium bromide ( CTAB) as a surfactant. Single- crystal ceria ( CeO2) triangular microplates have been fabricated by a thermal decomposition - oxidation process at 650 degrees C for 7 h using single- crystal Ce( OH) CO3 microplates as the precursor. The shape of the Ce( OH) CO3 microplate was sustained after thermal decomposition - oxidation to CeO2. The products were characterized by X- ray powder diffraction ( XRD), transmission electron microscopy ( TEM), field- emission scanning electron microscopy ( FE- SEM), differential scanning calorimetric analysis ( DSC), and thermogravimetric analysis (TG).