The results of nonisothermal kinetic analysis of the thermo-oxidative degradation in air and in oxygen of the copolymer EVA and nitrile-butadiene rubber (NBR) are presented. It was observed that similar processes take place at thermooxidative degradation in air as well as in oxygen of both investigated polymeric materials. The first process, which leads to solid products, is followed by thermo-oxidative degradation with the generation of volatile products. It has been shown that the first process of thermo-oxidation occurs at lower temperatures in oxygen than in air. For this process, the nonisothermal kinetic analysis was carried out using the Kissinger method. The obtained results revealed the importance of the oxygen pressure as an accelerator in the thermo-oxidative degradation of copolymer EVA and NBR. (C) 2000 John Wiley & Sons, Inc.