High-active Fe-Al and Cu-Fe-Al nanocomposite catalysts were synthesized by fusion of aluminium, iron, and copper salts and then tested in the oxidation of CO. It was found that the activity of Fe-Al catalysts depends on the Fe concentration and the maximum is achieved when the Fe2O3 content is approximately 82wt%. The addition of Cu leads to a significant increase in activity. Using adsorption techniques, X-ray diffraction, X-ray absorption spectroscopy, and Fourier-transform infrared spectroscopy, morphology, structure, and chemistry of the catalysts were studied. It was shown that the Fe-Al catalysts consist of Fe2O3 and Al2O3 phases mainly. Alumina is in an amorphous state whereas iron oxide forms nanoparticles with the protohematite structure. The Al3+ cations partially dissolute in the Fe2O3 lattice. X-ray absorption spectroscopy indicated that the Cu-Fe-Al catalysts in addition contain CuO and CuFe2O4 oxides in an amorphous state. [GRAPHICS] .