Abstract: TTHAformed a 1:1 complex with cerium (Ⅲ ) at pH5.5 that showed an absorption maximum at 279 nm with a molar absorptivity of 8.18×10²l·mol·cm^-1. Most of the rare earths and scandium in 10-fold amounts do not interfere. The second-derivative spectrum recorded from 320 to 240nm can be used to determine 5-80ppm of cerium. The method was applied to the determination of cerium in the mixtures of rare earth oxides with satisfactory results.