[en] The hydrogenated acrylonitrile-butadiene rubber, with a thermal stability up to 185 degrees C was subjected to accelerated thermal deflexion, DRC, to 15, 25, 35 and 50% constant deflexion. The irradiation used was Co sources for a dose rate of 4, 11 and 31.6 krad/h, corresponding to 25% constant deflexion. For 15,35 and 50% constant deflexion, the ageing was obtained at the temperature only for the constant deflexion corresponding to 17.1, 6.51, and 2.31 krad/h, adequate to constant deflexion of 15,35 and 50%. Due to the relaxation phenomena which take place in viscoelastic polymers, the agreed mechanisms models gave the material equations which are in very good concordance with the experimental results