Complex formation of cerium(III) with 1-phenyl-2,3-dimethylpyrazolone-5-azo-4-pyrogallole (L) in the presence and absence of 8-hydroxyquinoline (HQ) was investigated. It is revealed that homogeneous CeL and mixed ligand CeL–HQ compounds are formed at рН 6. Ratio of reagents in composition of homogeneous is 1:2 and in different ligand it equals to 1:2:2. The technique for photometric determination of cerium has been worked out in artificial mixture