A composition of formula
Ce1-a-b-cNaMbDcOx I
wherein M stands for one or more elements from the group of alkaline metals, except sodium, N is Bi and/or Sb, D is present, or is not present, and if present is selected from one or more of Mg, Ca, Sr, Ba; Y, La, Pr, Nd, Sm, Gd, Er; Fe, Zr, Nb, Al; a is a number within the range of 0<a≤0.9, b is a number within the range of 0<b≤0.3, c is a number within the range of 0<c≤0.2, a plus b plus c is <1, and x is a number within the range of 1.2≤x≤2, and its use for exhaust gas aftertreatment systems of Diesel engines, gasoline combustion engines, lean burn engines and power plants.