A planar iron-polyphthalocyanine (PPcFe) oxygen reduction reaction (ORR) catalyst for magnesium air fuel cells (MAFC) is prepared by dispersing PPcFe on carbon black (C) and heating under argon. Thermogravimetric analysis shows PPcFe is stable below 600 °C. The X-ray diffraction and X-ray photoelectron spectroscopy results show the active site of PPcFe/C is the FeN4 in the phthalocyanine ring. The rotating disk electrode measurements in 0.5 M L−1 H2SO4 solution show the initial potential for ORR is 0.82 V vs. RHE at 20 °C and that it mainly occurs via a four-electron process. Almost no performance degradation is observed over continuous cyclic voltammetry at 10,000 cycles, linear sweep voltammetry at 200 cycles, and 60 h of the chronoamperometry test. The infrared spectrum of PPcFe, after all the durability tests, shows no changes from the initial characteristics. The polarization curves of the air electrodes with PPcFe/C, iron-phthalocyanine/C and Pt/C catalysts exhibit excellent polarization performances. The discharge performance of a MAFC single cell with PPcFe/C cathode catalyst shows an open circuit potential of 1.74 V, with a peak power density of 50.5 mW cm−2 at 20 °C. The cell voltage decreases less than 0.01 V during continuing discharge @ 20 mA cm−2 for more than 11 h. Display omitted •A planar iron-polyphthalocyanine (PPcFe) with a large-area π bond is synthesized.•PPcFe/C exhibits high oxygen reduction activity.•Spectral and electrochemical studies show that PPcFe/C has excellent durability.•A magnesium/PPcFe/C-air cell has excellent discharge performance and stability.