In this paper, a multi-dimensional dynamic model of vanadium Redox Flow Batteries (RFB) is employed to predict battery performance and internal operating condition during charge and discharge. The model consists of a set of partial differential equations of mass, momentum, species, charges, and energy conservation, in conjunction with the electrode’s electrochemical reaction kinetics. After validated against experimental data for a vanadium RFB, flow field, temperature distribution, and reactant evolution are presented. The developed numerical tool is extremely useful in optimizing RFB design and control.