Proton Exchange Membrane Water Electrolysis (PEMWE) is crucial for hydrogen production but relies on scarce platinum group metals (PGMs) like platinum (Pt) and iridium oxide (IrO₂), limiting scalability. A key challenge is the sluggish oxygen evolution reaction (OER) and poor anode stability in acidic conditions, affecting efficiency.[1,2] This work aims to gain a thorough mechanistic understanding of a stable and active PGM-free OER catalyst based on manganese (Mn)-based material doped with niobium (Nb) and fluorine (F). Electrochemical operando XAS will probe catalyst’s structural and electronic properties, revealing how Nb and F enhance stability and activity in PEMWE.