Fuel cells have been identified as a promising energy solution, particularly in the quest for zero-emission vehicles. However, the use of platinum-based catalysts has posed a challenge. This article discusses a recent study published in *Nature Communications* that delves into the potential of the iron/nitrogen/carbon (Fe/N/C) system as an alternative catalyst for fuel cells. The research focuses on understanding the structural transformations that occur during the synthesis of Fe/N/C catalysts, crucial for optimizing their performance in the oxygen reduction reaction (ORR). By meticulously tracking the evolution of Fe species during pyrolysis, the study provides insights into the formation of active catalytic sites necessary for efficient ORR in fuel cells. Historically, iron oxides were not considered effective catalysts for ORR. However, recent advancements in embedding isolated iron atoms into a nitrogen-doped carbon matrix have shown promising results in creating efficient catalysts like Fe/N/C. The study highlights the specific conditions and transformations required to achieve active catalytic sites in these systems. The significance of this research lies in the potential for Fe/N/C catalysts to contribute to green energy systems by reducing the reliance on rare and expensive materials such as platinum. The findings offer a pathway towards sustainable energy solutions, aligning with the global shift towards cleaner transport systems. The study utilizes in situ diagnostic techniques to observe the structural evolution of Fe species in real time, revealing the step-by-step journey from iron chloride salts to advanced iron/nitrogen coordinated sites. Notably, the researchers found that the particle size of iron oxide significantly influences the morphological and structural transitions under heat, emphasizing the importance of proper heat treatment in enhancing catalytic activity. Overall, the study provides valuable insights into the potential of Fe/N/C catalysts for fuel cells and underscores the importance of optimizing catalysts for a more sustainable energy future.