In the present work, a series of iron based catalysts supported on ZSM-5 were prepared using incipient wetness method and tested for C-2-C-4 light olefins production from syngas (CO + H-2). The effects of Fe and Mn loading, calcination conditions, different promoters, wt.% K as an optimal promoter and operational conditions on the catalytic performance of the optimal catalyst were investigated. It was found that the catalyst containing 8% Fe/2.4%Mn/ZSM-5 promoted with 2 wt.%K had the best catalytic performance for light olefins production. The best operational conditions were H-2/CO = 2/1 M feed ratio, T = 270 degrees C, gas hourly space velocity (GHSV) = 2600 h(-1) and 1 bar pressure. Catalysts and precursors were characterized by X-ray diffraction (XRD), transmission electron microcopy (TEM), thermal gravimetric analysis (TGA), temperature program reduction (TPR), Scanning electron microcopy (SEM), differential scanning calorimetry (DSC) and N-2 adsorption-desorption measurements. The TPR spectrum for 8% Fe/2.4%Mn/ZSM-5 showed lower reduction temperatures respect to similar Fe-Mn catalysts. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.