A highly loaded bimetallic iron-cobalt catalyst was developed for hydrogen release from ammonia. The catalyst was synthesized from Mg(Fe,Co)₂O₄ spinel precursors through co-precipitation, calcination, and reduction. The resulting Fe-Co/MgO catalysts had an extraordinary high metal loading of 74 wt.%, combining the advantages of a ruthenium-like electronic structure with a bulk catalyst-like microstructure. The catalysts showed high activity for ammonia decomposition, with a steady-state H₂ production rate of 0.21 mol H₂ g⁻¹ h⁻¹ at 500 °C. However, the catalyst was found to undergo nitridation, which reduced its activity. By alloying iron with cobalt, the nitridation was suppressed, and the nitrogen binding energy was brought closer to that of ruthenium, leading to a highly active and stable catalyst. The bimetallic catalysts showed improved activity compared to monometallic Fe and Co catalysts, with the Fe₀.₅Co₀.₅/MgO catalyst demonstrating the highest performance. DFT calculations confirmed that the nitrogen binding energy of Fe₃N was too weak, making it less active. Alloying iron with cobalt suppressed nitridation and reduced the nitrogen binding energy, leading to a highly active catalyst. This work demonstrates that alloying iron with other metals with weak nitrogen adsorption energy provides a simple and general approach to fabricating a highly active and unnitrided catalyst for ammonia decomposition.A highly loaded bimetallic iron-cobalt catalyst was developed for hydrogen release from ammonia. The catalyst was synthesized from Mg(Fe,Co)₂O₄ spinel precursors through co-precipitation, calcination, and reduction. The resulting Fe-Co/MgO catalysts had an extraordinary high metal loading of 74 wt.%, combining the advantages of a ruthenium-like electronic structure with a bulk catalyst-like microstructure. The catalysts showed high activity for ammonia decomposition, with a steady-state H₂ production rate of 0.21 mol H₂ g⁻¹ h⁻¹ at 500 °C. However, the catalyst was found to undergo nitridation, which reduced its activity. By alloying iron with cobalt, the nitridation was suppressed, and the nitrogen binding energy was brought closer to that of ruthenium, leading to a highly active and stable catalyst. The bimetallic catalysts showed improved activity compared to monometallic Fe and Co catalysts, with the Fe₀.₅Co₀.₅/MgO catalyst demonstrating the highest performance. DFT calculations confirmed that the nitrogen binding energy of Fe₃N was too weak, making it less active. Alloying iron with cobalt suppressed nitridation and reduced the nitrogen binding energy, leading to a highly active catalyst. This work demonstrates that alloying iron with other metals with weak nitrogen adsorption energy provides a simple and general approach to fabricating a highly active and unnitrided catalyst for ammonia decomposition.