The effect of precursors of Co/γ-Al2O3 catalysts prepared from Co(NO3)2 and (CO)6Co2CC(COOH)2 on the Fischer-Tropsch synthesis (FTS) catalytic performance were investigated. All catalysts were characterised by TGA, BET, pore size distribution analysis and TEM techniques. For Aluminium-supported catalyst, the use of cobalt carbonyl cluster as cobalt precursor resulted in a higher activity and C5+ selectivities compared with the reference catalyst prepared from nitrate at low reaction temperature. The activities can be correlated with the zero valent cobalt metal exist on the support. The chain growth attribute to well dispersed smaller metallic cobalt particles resulted from the partial removal of terminal carbonyls at 150°C.