AbstractThe thermal oxidation of a film of isotactic polypropylene was studied using by infrared spectroscopy. Reaction temperatures varied from 120°–150°C. and oxygen concentrations from 7–100%, by volume. A reaction scheme was postulated and kinetic expressions were developed therefrom. These expressions could explain very well the experimental results obtained. An activation energy of 31 ± 1 kcal./mole was obtained for the initiation process whereas a value of 22 ± 1 kcal./mole was obtained for the process involving the formation of non‐volatile oxygenated s