The electrical properties of the interface between Hg0.8Cd0.2Te (MCT) and its oxide him prepared by anodic oxidation were estimated at 77 K. The surface charge states density Q(ss), fast surface states density N-ss, type of states of passivity anodic oxide films are obtained from capacitance-voltage measurement. The interface between MCT and its anodic oxide film is characterized by a fast surface states density of the order of N-ss = 7 x 10(10) eV(-1) cm(-2) near the middle of the bandgap and of N-ss approximate to 7 x 10(11) eV(-1) cm(-2) at fiat band voltage in accordance with fixed surface charge states density Q(ss) = 2 x 10(-8) C cm(-2) (for n-type samples). The fixed oxide surface charge states density is positive for both p-type and n-type MCT semiconductors.