Thermally stable high surface area nanocrystalline CeO₂ was synthesized via an aqueous sol–gel method using cerium hydroxide and urea as precursors. The CeO₂ sol is yellow colored and absorbs light over the range 200–500 nm. Nanocrystalline CeO₂ particles derived from the sol are spherical in shape and range from 9 to 13 nm in diameter. The CeO₂ powder has a high surface area of up to 85 m² g⁻¹ and a band gap of 3.1 eV. The method of preparation is facile, utilises low cost reagents and can be performed on a large scale.