In this computational study, we demonstrate the use of a high-fidelity multiphysics model to predict the effects of operational parameters and the performance of a new Solid Oxide Iron-Air Redox Battery (SOIARB) operated at 800 degrees C. The results show explicitly that the operating current density has the most pronounced effect on the H-2 concentration distribution, Nernst potential, specific energy and round-trip efficiency. The initial porosity in the Redox Cycle Unit (RCU) must be >0.50 at high current density in order to avoid significant diffusion limitation. Also, the distance between the RSOFC (reversible Solid Oxide Fuel Cell) and the RCU has little effect on the performance of the SOIARB, but has an appreciable effect on the chamber pressure. The simulations indicate that a high round-trip efficiency (RTE) can be achieved at the expense of useful capacity. Enhancement of the electrolysis electro-kinetics of RSOFC and FeO-reduction kinetics of RCU is a key to achieving high capacity with high efficiency.