自动氧化，是有机化合物与氧气分子在低温或适宜温度下发生的自由基链反应，反应产生氢过氧化物，氢过氧化物还可进一步分解。

烷、烯、醇、醛及酯类都容易发生自动氧化。

根据具体情况的不同，自动氧化可能是有益或有害的。涂料风干的过程中，自动氧化使涂料中的不饱和酯类转化为氢过氧化物，氢过氧化物在所添加的金属盐作用下，分解为烷氧基自由基，与其他烯烃进行反应，进而在表面形成一层可起保护作用的聚合物薄膜。而另一方面，脂的过氧化则是有害的，可导致细胞膜发生损害。

Autoxidation is any oxidation that occurs in open air or in presence of oxygen (and sometimes UV radiation) and forms peroxides and hydroperoxides. A classic example of autoxidation is that of simple ethers like diethyl ether, whose peroxides can be dangerously explosive. It can be considered to be a slow, flameless combustion of materials by reaction with oxygen. Autoxidation is important because it is a useful reaction for converting compounds to oxygenated derivatives, and also because it occurs in situations where it is not desired (as in the destructive cracking of the rubber in automobile tires or in rancidification).