The behavior of a direct-reduction, moving-bed reactor for the production of sponge iron from hematite is analyzed through the parametric study of the predictions obtained from a mathematical model previously presented by the same authors. The pellet-scale model is based on a three-moving-front scheme for the reduction of the various iron oxides, and it includes the water gas shift reaction (WGSR) in equilibrium in the sponge-iron layer. The reactor is modeled through a one-dimensional, heterogeneous, adiabatic, steady-state model. The numerical solution of the system of equations representing the problem is obtained by means of a novel solution scheme, since the conventional "shooting" method presented stability problems. Results from the models with and without inclusion of the WGSR are compared. The results obtained with the complete model that includes the WGSR introduce a significant advantage with regard to those brought about by simpler models. The complete model permits an accurate representation of pilot-plant reactors, including the ability to detect regions of optimal operating conditions.