[en] Manganese cobaltites MnCo₂O_4.62 and MnCo₂O_4.275 having a spinel structure were studied by measuring magnetization, AC susceptibility and by XANES spectroscopy. These compounds were synthesized by decomposition of the binary oxalate Mn_1/3Co_2/3C₂O₄.2H₂O in air at 220 and 500 deg. C, respectively. It was found that the differences in magnetic characteristics of these cation-deficient spinels are due mainly to variations in the degree of oxidation of manganese. It was shown that the complex oxide MnCo₂O_4.62 formed right after decomposition of the binary oxalate contains about 5x10^-4 mass% metallic cobalt, which determines the dependence of magnetic susceptibility χ on the magnetic field at 300 K. The magnetic transition peculiar to the stoichiometric spinel MnCo₂O₄ at 183 K decreases to 167.5 K for MnCo₂O_4.275 and 67.5 K for MnCo₂O_4.62