Direct catalytic conversion of syngas to light alkenes was carried out on sodium promoted FeMn catalysts by co-precipitation-calcination-impregnation method. N-2-physisorption demonstrated that the addition of sodium decreased surface area. H-2-TPR revealed that excessive sodium inhibited reduction of catalysts. XRD and MES results indicated that sodium made carburization easy. The results showed that the addition of Na/Fe in the range of 0.7-3.5 mol% could improve the light alkene selectivity in syngas conversion. A maximum in CO conversion and light olefin selectivity were noted upon increasing sodium content (2.8 mol% Na/Fe) and then declined. (C) 2014 Elsevier B.V. All rights reserved.