A series of solid solutions of bimetallic Ce/Zr-UiO-66 and -MOF-808 compounds with a varying ratio of Ce⁴⁺ to Zr⁴⁺ were obtained under mild reaction conditions within 15 min. The lattice parameters of the mixed-metal compounds are in accordance with Vegard's law. Samples with Ce ≤20 at% exhibit an enhanced thermal stability, better resistance against acids and smaller particle sizes.