The Dakin degradation equation leads to large errors in the thermal life prediction of cross-linkable polymers, especially where the mechanical properties and the relative elongation at break are concerned. For some cross-linkable polymers, a new thermal degradation equation has been proposed. Experimental data obtained in the accelerated thermal ageing of an EVA compound, based on poly(ethylene-co-vinyl acetate), antioxidants and fire proofing agents, obeys the new degradation equation.