Electrochemical energy storage, critical for resolving the unreliable and intermittent issues of the future renewable energy dominated electricity generation, plays a key role in achieving the goal of net-zero emission by 2050. Water electrolysis for hydrogen production and zinc-air battery are two important electrochemical energy storage technologies. Developments of cost-effective highly efficient and stable electrocatalysts for the fundamental electrochemical reactions involved in water electrolysis (hydrogen evolution reaction and oxygen evolution reaction) and zinc-air battery (oxygen reduction reaction and oxygen evolution reaction) are critical for their large scale applications. Single atom catalysts, because of their high utilization efficiency and intrinsic activities, become the focal materials for catalyst developments in recent years. This presentation illustrates applications of single atom catalysts for enhancement of electrochemical performances of water electrolysis and zinc-air battery.