Cobalt catalysts supported on SIRAL aluminosilicates have been prepared and tested in hydrocarbon synthesis from CO and H(2). It has been shown that the state of the cobalt metal on the catalyst surface is determined by both the cobalt content and the support nature, in particular, by the phase composition on its surface. The reaction rate on cobalt crystallites 3-6 nm in size is lower than that on 8-13-nm crystallites. It has been found that promotion with cerium oxide considerably increases the catalyst activity, although the selectivity for C(5+) hydrocarbons slightly decreases.