This work deals with a mechanistic scheme for polymer oxidation, in which the unique source of radicals is the unimolecular decomposition of hydroperoxides. The corresponding kinetic scheme is resolved in the general case where no stationary state for radical concentration is postulated. The numerical results are in good agreement with experimental data such as, for instance (a) the existence of a close relationship between the duration of the "induction period" and the reciprocal of the POOH decomposition rate constant, (b) the fact that the induction time tends toward a finite value when the initial POOH concentration tends toward zero, and (c) the fact that the steady state rate is independent of the POOH decomposition rate constant and that the apparent activation energy of oxidation varies with the exposure time. The practical use of this model appears, however, almost impossible, owing to the difficulty of determining certain parameters. Fortunately, a peculiar solution of the kinetic scheme based on the hypothesis of the existence of a stationary state for radical concentration displays the double advantage of having an analytical form and keeping all the predictive qualities of the general model, despite the wrong character of the starting hypothesis. This somewhat paradoxical result can be attributed to the structure of the basic differential equations and to the chosen ranges of parameter values. Ways for experimental checking of the model are proposed.