Impacts of K promoter on microstructures of a precipitated Cu-Fe based catalyst were studied by N-2-physisorption (BET), X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD) and hydrogen temperature-programmed desorption/reduction (H-2-TPD/TPR). Mixed alcohols synthesis (MAS) was carried out in a fixed-bed reactor. The results indicated that incorporation of K in the Cu-Fe based catalyst decreased the surface area of the particles, whereas promoted the immigration of bulky iron species to surface layers and strengthened the interaction of surface Fe-Cu. The increase of K concentration weakened the H-2 chemisorption and restrained the reduction of both the Cu and Fe species. The catalytic activity and mixed alcohols selectivity increased accompanied with a gradually increasing K concentration, and reached the highest values as the amount of K increased to 0.5 wt.%. Subsequently, the MAS activity and selectivity C2+OH presented a decreasing trend. In addition, the increase of K concentration facilitated the formation of heavy hydrocarbons. (C) 2014 Elsevier Ltd. All rights reserved.