Mass transfer limitations and kinetics studies were performed for Fischer-Tropsch Synthesis over spherical 10 wt% Fe-10wt% Co-0.5 wt% Pt/79.5 wt% γ-Al2O3 catalyst in a fixed bed reactor. The external mass transfer limitation was checked by studying the effect of gas hourly space velocity (GHSV) and feed flow rate (at constant GHSV) on CO conversion. Theoretical and practical methods were applied to assess the effect of catalyst pellet size on the internal mass transfer limitation. The results indicated there is external diffusion limitation for GHSV lower than 4,200 h-1. Both the theoretical and practical methods showed that the reaction is free of internal diffusion limitation with average particle sizes of 0.21 and 0.42 mm due to Thiele modulus smaller than 0.4, denoting that the rate of reaction is kinetically controlled. The kinetics results demonstrated the combined enol and carbide mechanism-based model was able to provide a good fit for the experimental data.