Understanding the overpotential of the Oxygen Reduction Reaction (ORR) at the cathode of Proton Exchange Membrane Fuel Cells (PEMFC) has been the focus of extensive research efforts. The framework introduced by Nørskov et al. which uses thermodynamic arguments to explain the overpotential is particularly insightful and has been used by numerous studies highlighting its significance in the field. Yet, alternative explanations for the overpotential have been explored to provide a more comprehensive understanding of the ORR. Notably, the presence of site-blocking species and parasitic reactions leading to mixed potentials. It has been shown that the ORR indeed proceeds more slowly on oxidized platinum catalysts. Similarly, it has been shown that specific intermediates can participate in non-electrochemical reactions such as the hydrolysis of O * further reducing the efficiency of the system. It is increasingly evident that the general solution to the ORR overpotential prediction likely lies in a combination of these factors.