The magnetic field dependence of the two-terminal magnetoresistance was used to measure the carrier density and mobility in the accumulation layer at the II-VI compound semiconductor Hg1-xCdxTe (MCT)-passivant interface. The interface was obtained by two different oxides: anodic oxide and electroless chemical oxide. The results of single-element photoconductive MCT detectors passivated by two different oxidation processes indicated that the carrier density in the accumulation layer is higher in the case of anodic oxide. The reason is that higher carrier density at the oxide/MCT interface creates a higher electric field which reduce the carrier recombination at the interface which is often a performance limiting factor.