[en] The results of the investigation into the temperature dependence of the destruction kinetics of previously induced M centres in MgF₂ on irradiation with a nanosecond electron pulse are presented. It is shown that the M centres are destroyed by two processes: the fast temperature - independent process and the long-term temperature-dependent one. From an analysis of the experimental data it follows that at increasing the time from the beginning of the irradiation pulse the value of the activation energy of the temperature-dependent process decreases from 0.19+-0.04 eV at t=20 ns to a value coinciding, within the error, with the one measured in the continuous-irradiation regime and equal to 0.1+-0.02 eV at t=1000 ns. The obtained results are explained by the theory of the mechanism of thermally activated space separation of the FH pair primary components. The obtained values of the activation energies of the space separation and migration of the H centres are equal to 0.09+-0.04 and 0.1+-0.02 eV respectively