Designing and optimizing the flow-field structure for the liquid phase Br-2/HBr electrolyte solution of H-2/Br-2 redox flow batteries (RFBs) is important for improving cell performance. In this study, two electrolyte flow modes, i.e. the flow-by and flow-through modes, are simulated by using a threedimensional H-2/Br-2 RFB model. The model is first applied to real-scale H-2/Br-2 cell geometries and then validated against the experimental polarization curves acquired using the two different flow modes. The model predictions cdmpare well with the experimental data and further highlight the advantages of using the flow-through mode relative to the flow-by mode. Detailed multi-dimensional contours of the electrolyte flow velocity and key species distributions reveal that more uniform diffusion and stronger convective transport are achieved by using the flow-through mode, which alleviates the ohmic loss associated with charge transport in the Br-2 electrode. (C) 2017 Elsevier Ltd. All rights reserved.