[en] The electrical reliability of HfO_2 based metal–insulator–metal capacitors is investigated under AC stress voltage. The capacitance–time (C–t) and conductance–time (G–t) responses are studied for different stress amplitudes and frequencies. Time-to-breakdown is observed to strongly depend on the electrode nature. Electrical degradation is discussed via a model based on oxygen vacancy/oxygen ions generation. Defect generation is controlled by the injecting nature of electrodes. Partial recovery, and so time-to-breakdown, are controlled by the ability of electrodes to store oxygen. (paper)