It is shown that the geometrical factor controlling a thermooxidative degradation course is effective spectral dimension d(s)' or factor beta. In turn, parameters d(s)' and beta are a function of a polymer melt structure characterized by its fractal dimension Delta(f). The applicability of this or that scaling relationship allows the evaluation of general features of chemical reactions in the thermooxidative degradation process. (C) 2004 Wiley Periodicals, Inc.