The present work focuses on the transfer and reaction phenomenon in a catalyst pellet for Fischer-Tropsch synthesis. It is considered that the pores of catalyst pellets are filled with liquid wax under Fischer-Tropsch synthesis conditions. The reactants in the bulk gas phase dissolve in the wax at the external surface of the pellet, and the dissolved components diffuse through the wax inside the pellet and react on the internal surface of the pellet. The thermodynamic equilibrium between the gases in the bulk and the liquid wax in the pores is correlated by a modified SRK equation of sate (MSRK EOS). On the basis of the phenomena observed from experiments, a comprehensive pellet model is suggested for catalyst design simulation, in which detailed Fischer-Tropsch mechanistic kinetics is properly imbedded. The reaction and diffusion interaction in a catalyst pellet and its effect on the product selectivity are further investigated. The potential of using eggshell-type catalyst pellets is explored as a means of decoupling the severe transport restriction and, hence, enhancing the overall selectivity of desired products.