Citrate-nitrate method was used to synthesize (Fe,Co)/MgO-Al 2 O 3 , (Fe,Mo)/MgO-Al 2 O 3 , and (CoMo)/MgO-Al 2 O 3 catalysts for production of carbon nanotubes. Multi-walled nanotubes were formed on these catalysts by catalytic pyrolysis of a propane-butane mixture.Carbon nanotubes (CNTs) are of great interest for scientists and applied researchers in various fi elds of science and technology owing to their unique electrical, mechanical, and physical properties. The quality of the CNTs synthesized is affected by numerous factors including the chemical nature of a catalyst, method for synthesis of nanotubes, type of a gas mixture, and synthesis temperature.CNTs are synthesized by the CVD method (gas-phase catalytic pyrolysis of carbon-containing substances) most frequently on metal oxide catalysts. As the main catalytically active components serve such metals as Fe, Mo, Co, and Ni, and more rarely Mn, V, and W. These metals exhibit the highest catalytic activity in synthesis of nanotubes.In most of studies [1-13], preference is given to bimetallic catalysts. Systems of this kind have an increased activity and selectivity and a large specifi c surface area. The yield of nanotubes was evaluated in the present study by the difference of masses of the product and starting catalyst, related to unit mass of the catalyst. The selectivity means that it is possible to obtain nanotubes with certain geometric and structural parameters (diameter, length, positions of graphene layers, etc.) on a catalyst.There still is no unambiguous interpretation of why the activity of catalysts for CNT growth increases upon introduction of more than one transition metal into their composition. Judging from published data [13][14][15][16][17][18][19][20], we can assume that in two-and many-component catalytic systems Mo-(Fe, Co, Ni), Fe-Co, and Fe-Ni, presence of a second metal (co-catalyst) leads to the following effects.(1) Formation of heterometaloxane structures (e.g., heteropolymolybdates, ferrites) in the starting metal oxide catalysts, which favors formation and stabilization of metallic particles of smaller size in the course of reduction of the metal oxide catalysts in the CNT-synthesis reactor.(2) Hindered sintering of active nanosize metal clusters into coarse poorly active catalytic particles.(3) Hindered crystallization of the carbide of the metal predominant in the system, which can deactivate the catalyst in CNT growth because of the slower diffusion of carbon in crystalline metal carbides, compared with solutions of carbon in metals (for example, crystalline iron carbide Fe 3 C is inactive in decomposition of a hydrocarbon [16]).(4) Formation of crystalline molybdenum carbide, which improves the dispersity and catalytic activity of