Abstract: An iron/chromium redox flow cell system (270W) was constructed with polyarylonitrile graphite felt electrodes. Its bipolar plates were graphite plates soaked with paraffin. The positive and negative compartments were separated by the cation exchange membranes made of polystyrene sulfonic acid. The electrocatalyst for negative electrode was Pb-Bi combination electrodepos-ited before the operation of the system, which was also a negative electrode hydrogen evolution inhibitor. The measurements of the redox system showed its high stability in performance during the period of about 120 charging and discharging cycles. The current, voltage and energy efficiencies of the system were 93%, 78% and 72% respectively.