Two preparation techniques (incipient-wetness impregnation and ion exchange) have been used to prepare NaX and NaY zeolite-supported cobalt catalysts. These catalysts were characterized by X-ray diffraction, temperature-programmed reduction, and temperature-programmed desorption of hydrogen. The Fischer-Tropsch synthesis was examined at temperatures in the range of 220-300-degrees-C, a pressure of 1 atm, a CO/H-2 ratio of 1, and flow rate of GHSV=1200. The mobility of cobalt ions inside the zeolite cages in the ion-exchanged samples caused the difficulty in reduction and less active sites for the access of CO to the metals which are entraped in the sodalite cage. The ion-exchaned catalyst thus disclosed a low catalytic activity. The absence of hydroxyl group in the impregnated catalysts results in the stabilization of the metallic form of cobalt on the external surface of zeolite which cause catalytic activity in the FT reaction. The Co/X catalysts always exhibited higher activities than the Co/Y catalysts, no matter what preparation method was followed.