CO-TPD and H-2-TPD and CO/H-2-TPSR were used to study the effect of the support on the performance of Fe-MnO catalysts in CO hydrogenation for the production of light olefins. It was found that a Fe-MnO/MgO catalyst (based on a basic support) is capable of strongly adsorbing CO and H-2 favorable for the production of light olefins and CO conversion. A Fe-MnO/Al2O3 catalyst (based on an acidic support) only showed strong adsorption of H-2, but weaker adsorption of CO, and so, it was a poor catalyst for light olefins from syngas.