In order to increase the catalyst activity for Fischer-Tropsch synthesis (FTS), the preparation methods of two new catalysts were studied. The chemically identical bimetallic Co-Mn/Al 2 O 3 catalysts were synthesized by different synthetic methods: (a) via thermal decomposition of the complex [Co 1.33 Mn 0.667 (C 7 H 3 NO 4) 2 (H 2 O) 5 ].2H 2 O (1) and (b) by the impregnation technique. The complex was characterized by the single-crystal analysis, elemental analysis, and Fourier-transform infrared (FT-IR) spectroscopy. Both catalysts were characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectrometry (EDS), Brunauer-Emmett-Teller (BET) specific surface area, hydrogen temperature-programmed reduction (H 2-TPR), and H 2-chemisorption. The catalysts' activity was investigated for the Fischer-Tropsch synthesis in a fixed bed microreactor. Higher activity was obtained for the catalyst prepared by thermal decomposition of the inorganic precursor due to its small particle size, superior dispersion, and higher surface area. The results show that the catalyst prepared thermal decomposition has 21% ethylene, 10% propylene, and 50% C 5 + selectivity, while methane selectivity of this catalyst is 11% at 250 C. On the other hand, the catalyst obtained by the impregnation method displays 15% ethylene, 8% propylene, 29% C 5 + , and 29% methane selectivity at the same temperature.