Selective production of gasoline ranged iso-paraffins from synthesis gas was performed in a consecutive dual reactor system, in which Fischer-Tropsch reaction was carried out over Co/SiO2 catalyst in the upper reactor and hydroconversion of the Fischer-Tropsch hydrocarbons occurred over precious metal/zeolite catalyst in the lower reactor. Results indicate that the product distribution of traditional Fischer-Tropsch synthesis was significantly modified and high selectivity to iso-paraffins was achieved with the presence of metal/zeolite catalyst in the lower reactor. A significant effect of metals (Pt and Pd), zeolites (zeolites of beta and USY), and the preparation methods (impregnation and ion exchange) of the metal/zeolite catalyst on the iso-paraffins selectivity and product distribution was clearly observed. This was explained based on the property of the metal for hydrogen spillover and the acidic and structural properties of the zeolite in the bifunctional metal/zeolite catalyst. (C) 2006 Elsevier B.V. All rights reserved.