The sorption capacity and resistance to thermooxidative degradation are comparatively studied for isotactic polypropylene (PP) produced in the medium of the liquid monomer on homogeneous metallocene catalytic systems and on a heterogeneous titanium-magnesium catalyst. These polymers are characterized by different sorption capacities with respect to the phenyl-p-naphthylamine antioxidant and different induction periods of oxidation by molecular oxygen. (c) 2005 Wiley Periodicals, Inc.