Iron molten air batteries are an attractive technology for electrical energy storage because of advantages of higher capacity, low cost, sustainability, and environmental friendliness compared to existing secondary batteries; however, battery applications still suffer from low coulombic efficiency and poor cycle stability. Here we report design of a robust fin air electrode for the iron molten air battery. The battery cycled stably at 500 degrees C for 80 cycles with an average discharge potential of similar to 1.04 V and average charging potential of similar to 1.20 V. The highest coulombic efficiency reaches 93.4% to a 0.7 V discharge cutoff. The encouraging performance offers hope to design more advanced air electrodes for iron molten air batteries. (C) 2016 The Electrochemical Society. All rights reserved.