Novel cerium (IV) oxidic compounds, well suited as catalysts, e.g., for the clean combustion of hydrocarbon fuels and for the "drying" of paint compositions, each Ce(IV) atom of which being coordinated with two anions of an organic oxyacid advantageously having a pKa greater than 1, preferably greater than 2, or a mixture of such oxyacids, and the oxidic oxygen atom or atoms of which being other than those comprising the organic oxyacids; representative such novel cerium (IV) oxidic compounds, whether yellow crystalline solids or yellow liquids, have the formula: (H.sub.2 O).sub.p �Ceo(A).sub.2.(AH).sub.n.!.sub.m in which the radicals A, which may be the same or different, are each the residue of an organic oxyacid of formula AH, p is an integer ranging from 0 to 5, n ranges from 0 to 2 and m is an integer ranging from 1 to 12.