Effect of potassium and ceria promotion on the activity and selectivity of Co/SiO2 catalyst was investigated for CO hydrogenation in a high pressure reactor. Five different SiO2 supported cobalt catalysts promoted with K and CeO2 were synthesised by sol gel followed and wet impregnation. These catalysts were characterised by BET surface area, pore volume, TGA, TPR, SEM, TEM, and chemisorptions methods. The cobalt particles were well dispersed in sol gel method in presence of complexing agent. The major phase obtained was Co3O4 and the average metal particle size as determined from the hydrogen chemisorptions and TEM studies varied from 20 to 60 nm. The performance of these catalysts were compared at 250 degrees C and 20 bar pressure and at a weight hourly space time of (W/F-o) 1000 kg(catalyst) s/N m(3). Incorporation of K and CeO2 significantly influenced the catalyst reducibility due to increased metal support interaction. The CO conversion and C5+ selectivity were highest for ceria doped Co/SiO2 catalyst. Both K and CeO2 promoted Co/SiO2 were found active and stable for the FTS reaction, however compared to K promoted catalyst ceria promoted catalyst notably improved the C5+ selectivity, while suppressing the CH4 and coke formation. (C) 2012 Elsevier Ltd. All rights reserved.