Yu, Hsiang‐ChunHsiang‐ChunYuLin, Yu‐RuYu‐RuLinPeng, Chun‐KuoChun‐KuoPengLin, Yi‐DongYi‐DongLinLin, Yu‐ChangYu‐ChangLinHuang, Shih‐ChingShih‐ChingHuangChen, Hao MingHao MingChenLin, Yan‐GuYan‐GuLin2025-07-182025-07-182025-04-24https://scholars.lib.ntu.edu.tw/handle/123456789/730750Electrochemical processes involving electrified solid–liquid interfaces are pivotal in the area of catalysis reaction. Nevertheless, the microscopic characteristics of these catalytic interfaces, particularly the structural transformations they undergo during reactions, have yet to be fully understood—posing considerable implications for practical applications. Exploring the interface between catalysts and electrolytes can provide valuable insights into the development of a concise electrocatalytic mechanism. Advanced synchrotron X-ray methodologies have demonstrated their efficacy in analyzing the structural and electronic characteristics of electrocatalysts. Combined with in situ/operando techniques, these approaches successfully illuminate dynamic transformations and unveil the genuine active sites. In this review, a comprehensive overview of the latest advancements in key in situ/operando techniques, such as scattering and spectroscopy, highlighting their current limitations and challenges, is provided. Building on the core principles of these techniques, their robust characterization capabilities are explored for revealing and understanding electrocatalytic mechanisms. Finally, to address the complexity of catalytic processes, “in situ/operando electrocatalytic mechanism probing map” specifically designed for liquid–solid interfaces, offering a clear guide to systematically uncover the fundamental nature of electrocatalytic mechanisms, is proposed.endynamicselectrocatalystsin situ/operando techniquessolid–liquid interfacessynchrotron radiation techniques[SDGs]SDG7journal article10.1002/aesr.202500029