The effects of [Fe]/[Mn] molar ratios, promoters, loading of optimal promoter and calcination conditions on the catalytic performance of iron-manganese catalysts for the Fisher-Tropsch synthesis (FTS) were investigated. It was found that the 50%Fe/50%Mn catalyst that was promoted wills 6 wt.% K is an optimal catalyst for the conversion of synthesis gas to hydrocarbons especially light olefins. The effects of calcination behaviors and operational conditions on the catalytic performance of optimal catalyst were investigated. The results are shown that the best operational conditions are the H-2/CO = 2/1 molar feed ratio at 280 degrees C and GHSV = 1400 h(-1) under 3 bar total pressure. Characterization of catalysts were carried out using X-ray diffraction (XRD), temperature program reduction (TPR). thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC), and the N-2 adsorption-desorption measurements such as Brunauer-Emmett-Teller (BET) and Barrett Joyner-Halenda (BJH) methods. (C) 2011 Elsevier B.V. All rights reserved.