Fischer-Tropsch synthesis was studied by using a combination of promoted and unpromoted cobalt catalysts in a dual bed reactor. An alkali-promoted catalyst was used in the first bed of a fixed-bed reactor followed by an unpromoted catalyst in the second bed. The activity and product selectivity of the system were assessed and compared with those using a mixture of both catalysts in a single bed. The methane selectivity in the dual bed reactor was about 17% less compared to that of the single bed reactor. The C5+ selectivity for the dual bed reactor was 12.3% higher than that of the single bed reactor. (C) 2006 Elsevier B.V. All rights reserved.