Water electrolysis stands as a cornerstone of global sustainable energy systems, enabling the generation of hydrogen fuel for various applications. The article discusses the importance of developing efficient and stable anode materials for the Oxygen Evolution Reaction (OER) to advance Proton Exchange Membrane water electrolysis technology. Specifically, it highlights the research on amorphous hydrous iridium oxides (am-hydr-IrOx) due to their high activity but limited application caused by iridium dissolution. A collaborative effort led by scientists from Helmholtz-Zentrum Berlin and Fritz-Haber-Institut delves into the mechanisms of OER and Ir dissolution in am-hydr-IrOx, challenging previous understandings. Through the use of Hydrous Iridium Oxide Thin Films (HIROFs) as a model system, in situ X-ray techniques and Density Functional Theory (DFT) were employed to investigate the local structures, leading to the introduction of a new nanosheet model. The study reveals a unique iridium suboxide species linked to high OER activity and identifies Ir dissolution as a spontaneous process. Additionally, the research offers insights into the relationship between activity and stability of am-hydr-IrOx, presenting a new mechanistic framework that challenges conventional perspectives and provides a more accurate model. The findings are expected to guide the development of advanced anode materials for PEM electrolysis, contributing to the shift towards a low-carbon economy.