The addition of a small amount of SiO2- to Al2O3-supported cobalt catalyst significantly increased the reduction degree of the supported cobalt oxides and the metallic cobalt surface area, as a result of remarkable enhancement of the Fischer-Tropsch synthesis (FTS) activity in the slurry-phase reaction. Properties of various catalysts were characterized by in situ DRIFT, XRD, TPR, N-2 physisorption and H-2 chemisorption. Furthermore, properties and reaction performances of the present catalyst system were compared with those of Al2O3-promoted Co/SiO2 catalyst. (C) 2010 Elsevier B.V. All rights reserved.