It is shown that scaling relationships adequately describe the process of oxygen consumption in the course of thermooxidative degradation of poly(arylatearylene sulfonoxide). The correspondence of the experimental curve amount of the consumed oxygen time to one or another scaling relationship allows the definition of the mechanism of thermooxidative degradation. So, for poly(arylatearylene sulfonoxide), the mode of autodeceleration corresponds to the attack by oxygen molecules of the polymeric macromolecules reactive centers, and the mode of autoacceleration corresponds to the reaction of low molecular radicals. (C) 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 1760-1763, 2003.