Electrocatalysts are the core components of many sustainable energy conversion technologies that are considered the most promising solution to the worldwide energy and environmental crises. The reliability of the structure and composition indicates that electrocatalysts can achieve predictable and stable performance. However, during the electrochemical reaction, electrocatalysts are influenced directly by the applied potential, the electrolyte, and the adsorption/desorption of reactive species, triggering structural and compositional corrosion, which directly affects the catalytic behaviors of electrocatalysts (performance degradation or enhancement) and invalidates the established structure–activity relationship. In this talk, I will introduce our recent work on corrosion chemistry in electrocatalysts. We hope this topic will raise more awareness regarding nanomaterial corrosion chemistry in energy technologies and beyond.