Cycloolefin copolymers are used in different engineering applications and have been considered as packaging materials due to their brightness and transparency. For this application, it is relevant to study their degradative behaviour. The use of pro-degradant additives containing metal ions, which accelerate oxo - degradation, has been proposed to improve degradability of conventional polymers in the environment. In this research, ethylene-norbornene copolymers mixed with iron and manganese stearates were used as raw material to manufacture extruded flat films with thickness of 50 µm ± 5 µm. The films were subjected to accelerated conditions of photo-oxidative and thermo-oxidative degradation. Degradation was monitored through the measurement of tensile mechanical properties, infrared spectroscopy and carbonyl index. As a result, it was evidenced that pro-oxidants accelerated property changes in the films subjected to different degradative conditions. The carbonyl index showed the progress of the degradation reaction. Iron stearate had greater influence on films properties under photo-oxidative conditions, while the films containing manganese stearate demonstrated greater influence under thermo-oxidative conditions.