Capacitance-voltage characteristics (CV characteristics) of MIS structures based on graded-gap MBE Hg1–xCdxTe (x = 0.22–0.23) with a two-layer plasma-chemical insulator SiO2/Si3N4 are studied under variation of the voltage sweep direction. Special features are revealed in the CV characteristics at the forward and reverse voltage sweeps for MIS structures based on n-HgCdTe and p-HgCdTe. The results obtained suggest that the electron capture by states of the transition layer between the HgCdTe semiconductor and SiO2 insulator plays an important role in the hysteresis phenomena. It is found that if an insulator is applied, the impurity-defect centers of donor type are formed near the interface, whose density of states in the transition layer is (0.6–2.1)·1011 сm–2.