Oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) are among the core electrochemical processes in clean energy conversion and storage devices, such as metal-air batteries, water electrolyzers, and fuel cells. Single-atom catalysts have emerged as a new frontier of heterogeneous catalysts for these reactions due to their highly increased coverage of active sites, enhanced catalytic performance, and maximal metal utilization. By using machine learning algorithms, researchers provide a new paradigm for directly predicting the catalytic performance from physical properties of catalyst candidates.