This paper addresses the development of a mathematical model for a fixed-bed reactor where the Fischer-Tropsch synthesis reaction takes place. The model includes the consumption rate of carbon monoxide and the production rates for paraffin and olefin chains (up to the length of 47). The kinetic parameters are estimated using the experimental data under various experimental conditions with the effect of temperature, space velocity, the composition of feed mixture and pressure included. The simulation results with the estimated parameters predict the CO conversion, methane selectivity, paraffin selectivity and the entire distribution of hydrocarbon products satisfactorily. A further investigation on the effect of operating conditions shows that the ratio of hydrogen to carbon monoxide and the pressure are the effective variables for the determination of the entire distribution.