The study of influence of manganese (II) amount in a precursor of MnOх/Al2O3 catalysts for hydrocarbon deep oxidation is perspective for technologies of catalysts. The main aim of the study is to investigate the influence of Mn (II) amount in nanofibrous aluminum oxyhydroxide - a precursor of MnOх/Al2O3 catalysts - on phase structure and regularities in deep oxidation of C1-C3-alkanes. The methods used in the study: chromatography, X-ray analysis. The results: The authors have synthesized nanofibrous aluminum oxyhydroxide (AlOOH), modified with different amounts of manganese ions (II), which is the precursor for methane deep oxidation catalysts. It was shown that the modified catalyst as full aluminum oxyhydroxide can work only in preliminary thermal activation at 850 °C. The paper demonstrates that the catalysts with 10,5 mas. % Mn (II) is more perspective as the catalyst of hydrocarbon deep oxidation in spite of the fact that methane oxidation speed on it is lower, than on the catalyst with 5,7 mas. % Mn (II). In comparison with the catalyst with 5,7 mas. % Mn (II) where aluminum oxide is in metastable form (σ-Al2O3) the catalyst with 10,5 mas. % Mn (II) contains in the structure thermodynamically and thermally stable phase α- Al2O3, that allows this catalyst to work over the entire temperature range of C1-C3 hydrocarbon oxidation.