MCM-48 molecule sieve was used as a support of cobalt catalyst for Fischer-Tropsch synthesis (FrS). Co/MCM-48 catalysts were prepared using incipient witness impregnation method with cobalt loadings of 5, 10 and 15 wt.%, respectively. The catalysts were characterized by N-2 physisorption, X-ray diffraction (XRD), temperature programmed reduction (TPR), hydrogen temperature programmed desorption (H-2-TPD) followed by pulse oxygen titration and transmission electron microscopy (TEM). The catalytic properties for FTS were tested in a fixed bed reactor. TPR and oxygen titration indicated different extent of overall reduction of Co cobalt species in different cobalt content catalysts. With increasing Co loading, CO conversion and C5+ selectivity first increased remarkably and then remained nearly invariable. Lower reducibility of smaller cobalt particles on 5Co/MCM-48 is likely to be one of the reasons responsible for the lower CO conversion and highest methane selectivity. Co loading exceeding 10 wt.% had no significant effect on FrS properties of the catalysts. (c) 2005 Elsevier B.V. All rights reserved.