A kinetic and mechanistic study of the autoxidation of liquid pentaerythrityl tetraheptanoate (PETH) a t 180-22OOC has been carried out utilizing a stirred-flow reactor. The results are consistent with the occurrence of a chain reaction scheme similar to that proposed for n -hexadecane autoxidation, namely, the formation of monohydroperoxides by the intermolecular abstraction reaction (3), the formation of a,?-and cu,d-dihydroperoxides and a,?-and a,b-hydroperoxyketones by intramolecular peroxy radical abstraction reactions (4) and (4*), the bimolecular termination of peroxy radicals, reaction (61, and the rapid conversion of a,?-hydroperoxyketones to the corresponding cleavage acids and methyl ketones, reaction (7). Comparisons ofvarious rate parameters for the n-hexadecane and PETH systems reveal that the values of k7 and (k&l atom)/(2 hfi)1/2 are within experimental uncertainties identical for the two systems a t 180°C. The proposed reaction scheme includes the concurrent formation of hydroxy radicals and hydroperoxyketone species. The results of kinetic analysis and the experimentally observed isomer distributions of primary and secondary monohydroperoxide products a t high and low oxygen pressures suggest that ~6 0 % of the hydrogen abstractions from PETH a t high oxygen pressures occur by hydroxy radicals.