The present invention combines the storage capacity of redox flow batteries and the production of hydrogen and other products of chemical redox reactions. The redox couple of each electrolyte is chemically regenerated on a specific catalyst bed 11, replacing the discharging processes of the battery, whilst oxidizing or reducing other species present. This allows for the production of hydrogen on the cathodic side, and various useful products on the anodic side, such as oxygen for fuel cell application. The proposed system uses a dual circuit arrangement from which electrolytes 8 may be pumped through the catalyst beds 11 as desired, once they are in their charged state.