脂质过氧化（英语：Lipid peroxidation），即脂类氧化降解的一种过程。反应中，引发剂自由基（如氢氧自由基等活性氧物种）首先夺取不饱和脂的烯丙位氢，产生相应的自由基。该自由基再与氧分子作用，生成相应的过氧自由基，它夺取另一分子的烯丙位氢，转化为氢过氧化物。

过氧化是链反应，常见于多不饱和脂肪酸中，产物可能具有致癌和致诱变性。因脂类是细胞膜的组分，脂的过氧化如果不经控制可能会有灾难性的后果。体内由维生素E、超氧化物歧化酶、过氧化氢酶、过氧化物酶等控制这一过程。

Lipid peroxidation is the oxidative degradation of lipids. It is the process in which free radicals "steal" electrons from the lipids in cell membranes, resulting in cell damage. This process proceeds by a free radical chain reaction mechanism. It most often affects polyunsaturated fatty acids, because they contain multiple double bonds in between which lie methylene bridges (-CH₂-) that possess especially reactive hydrogen atoms. As with any radical reaction, the reaction consists of three major steps: initiation, propagation, and termination. The chemical products of this oxidation are known as lipid peroxides or lipid oxidation products (LOPs).