An oxidising agent (oxidant) is the reactant that accepts electrons in a redox reaction and is therefore itself reduced. By taking electrons from another species, it causes that species to be oxidised. Oxygen and chlorine are common oxidising agents; an oxidising agent contrasts with a reducing agent, which donates electrons.

氧化剂是氧化还原反应中接受电子的反应物,因而自身被还原。它通过夺取另一物质的电子,使该物质被氧化。氧气和氯气是常见的氧化剂;氧化剂与提供电子的还原剂相对。