The influence of Al2O3 promoter on a performance of C-1-C-14 alpha-alcohols direct synthesis from syngas over activated carbon (AC) supported cobalt catalysts (Co/AC catalysts) was investigated using CO hydrogenation evaluation, XRD, HRTEM, H-2-TPR, pulsed CO chemisorption, H-2-TPD and N-2 physisorption techniques. The results obtained showed that the addition of Al2O3 increased significantly the Co component dispersion without remarkably decreasing its reducibility and inhibited its aggregation during reaction, resulting in greatly enhanced reaction activity as well as increased selectivity towards liquid products. Appropriate amounts of Al2O3 can promote the formation of Co2C, leading to an increase of total alcohol fraction in the liquid products. Moreover, the Al2O3 addition can further promote the formation of higher alcohols (C-6-C-14 alcohols).