In our studies, we propose the use of natural, pro-ecological substances, such as flavonoids to protect elastomers against ageing. One of these substances, namely morin hydrate, was incorporated into ethylene–octene rubbers (Engage); then the vulcanisates of Engage containing the antioxidant under investigation were subjected to ageing processes. The changes in deformation energy, colour and cross-linking density and OIT index of the vulcanisates of Engage were measured before and after each ageing process. The test results obtained show that morin hydrate has a very positive influence on the stability of the vulcanisates of Engage, protecting them against the negative effects of ageing. In addition to its anti-oxidative function, morin hydrate changes the colour of the final polymeric product, fulfilling the role of a natural pigment. Thus, morin hydrate is not only a natural antioxidant but also a pigment in the polymers, imparting to them the features of pro-ecological materials.