The present work describes models for predicting concentration profiles of various species in each of the reactors present in a fuel processing system including a steam reformer, water gas-shift reactor and a preferential oxidation reactor. These reactor models incorporate phenomenological reaction schemes in power law format in order to predict the conversion of the species as a function of concentration and temperature. A surface film approach is used rather than the more traditional two-dimensional boundary layer in order to model the gas on the surface of the catalyst. The modeling framework is built within the Matlab Simulink environment to take advantage of available numerical schemes and optimization algorithms. Only steady state operation is considered for the reactors with validation occurring against experimental data obtained from the literature. In addition, temperature gradients within the reactors are imposed in order to eliminate the need to model the energy equation of motion. Parametric studies are performed on each of the individual reactors by varying the length, catalyst loading, catalyst dispersion and the effect of temperature drop across the reactor.