The H-2-Ce redox flow cell is optimized using commercially-available cell materials. Cell performance is found to be sensitive to the upper charge cutoff voltage, membrane boiling pretreatment, methanesulfonic-acid concentration, (+) electrode surface area and flow pattern, and operating temperature. Performance is relatively insensitive to membrane thickness, Cerium concentration, and all features of the (-) electrode including hydrogen flow. Cell performance appears to be limited by mass transport and kinetics in the cerium (+) electrode. Maximum discharge power of 895 mW cm(-2) was observed at 60 degrees C; an energy efficiency of 90% was achieved at 50 degrees C. The H-2-Ce cell is promising for energy storage assuming one can optimize Ce reaction kinetics and electrolyte. (C) 2016 Elsevier B.V. All rights reserved.