A series of calcium oxide promoted cobalt catalysts were prepared by incipient wetness impregnation. The influence of the calcium oxide on the dispersion. reducibility and cobalt particle size of the catalysts was Studied by different techniques, including N-2 adsorption. X-ray diffraction, temperature-programmed reduction, temperature-programmed desorption and oxygen titration. It Was found that calcium oxide improved the cobalt oxide reducibility, especially for the reduction of CoO to Co-0. Since the interaction between cobalt oxide and the calcium oxide promoted support was suppressed, larger Co3O4 Particles were formed on the Surface. The catalytic activity for Fischer-Tropsch synthesis was evaluated in a continuous stirred tank reactor (CSTR). A positive correlation was observed between CO conversion, C-5 degrees selectivity and calcium oxide content. Furthermore, methane selectivity decreased with increasing calcium oxide content. These Could be attributed to the enhanced reducibility that provides abundant active sites. (c) 2009 Published by Elsevier B.V.