High dispersion Co3O4 nano-particles supported on hollow mesoporous silica spheres (HMSS) with bimodal pore distribution were prepared by "two-solvent" technique. As-synthesized catalysts were characterized by XRD, N-2 adsorption-desorption, XPS, SEM, TEM, and H-2-TPR. The results showed that Co3O4 nano-particles were present inside the pore system of HMSS and the particles sizes increased with the increasing loaded cobalt content. The catalysts show good performance and high selectivity of C-5-C-18 hydrocarbon in F-T synthesis, which should attribute to the unique bimodal pore distribution facilitating reactants to access the active sites and to transport higher hydrocarbon products. (C) 2009 Elsevier B.V. All rights reserved.