The invention concerns the use of cerium dioxide, especially in the form of discrete cerium dioxide particles with particle sizes in the range from 0.005 to 150 μm, as inorganic radical trap to stabilize organic polymers, especially in the form of polymer-based formulations, varnishes, paints, coating compounds, or the like, against their photochemically, thermally, physically and/or chemically induced degradation by free radicals, especially against the effect of UV, advantageously in an optional combination with at least one UV-absorber and/or at least one additional radical trap. The radical-induced degradation of the organic polymers is effectively prevented by the use of cerium dioxide without the cerium dioxide itself becoming degraded. If a combination of cerium dioxide with an additional UV-absorber or radical trap is used, its effectiveness is extended through the presence of the cerium dioxide.