Alkaline-based organic redox flow batteries (AORFBs) attract significant interest because they can retain the advantages of vanadium redox flow batteries (VRFBs) while being low-cost because expensive vanadium is replaced with easily synthesizable metal-free organic compounds and earth-abundant raw materials. A comprehensive experimental study on the performance of AORFBs using alloxazine 7/8-carboxylic acid (ACA) and ferrocyanide was conducted to investigate the feasibility of these batteries as large-scale energy storage systems. The operating conditions, such as the electrolyte concentration, flowrate, and temperature, were varied in this study. The results show that the present AORFB achieves an energy efficiency above 76% at 80 mA cm(-2) at elevated temperature (55 degrees C). Compared with those of VRFBs, AORFBs exhibit very good thermal stability and capacity retention. A large-scale AORFB was constructed and tested to confirm the effectiveness of AORFBs.