It has been found that the CNFs are promising as supports to achieve high activity and selectivity due to their mesoporous structure, high mechanical strengths, high surface areas. More importantly, it was found that the activity and selectivity of F-T ca talysts depends significantly on the Co crystal size and the graphite orientation of the CNFs. The present work will prepare Co nanoparticles with well controlled size, shape and composition supported on carbon nanofibers with different graphite sheet ori entations in terms of the axis of fibers. The sample will be tested in both low and high pressures. Different characterization techniques will be used to study the interaction between CNF and Co, their effect on the Co properties including adsorption prop erties of CO, H2 and H2O. The research will focus on identification of controlling factors to control the activity and selectivity of Co catalyst in F-T synthesis. The experimental results and the results from DFT calculations will be implemented in a mic rokinetic model, which can be further used as a tool for rational catalyst design.