What does autoxidation mean?
Autoxidation is the slow, spontaneous reaction by which a substance combines with oxygen from the air at ordinary temperatures, without needing a flame, spark, or added heat. It differs from combustion chiefly in speed: both are oxidation reactions, but autoxidation unfolds gradually over hours, months, or years. The process is responsible for many familiar kinds of everyday decay — butter and cooking oils turning rancid, rubber becoming brittle and cracked, and drying oils like linseed oil hardening into paint films. Because it degrades foods, fuels, polymers, and pharmaceuticals, autoxidation is a central concern in food science and materials chemistry, where antioxidants are deployed precisely to inhibit it. The word is technical rather than colloquial, appearing mainly in scientific writing, yet it names a phenomenon so pervasive that understanding it explains much about how goods age and how they are preserved. It derives ultimately from Greek roots meaning "self" and the chemistry of oxygen.
nounThe spontaneous oxidation of a substance when exposed to oxygen in the air, occurring slowly at ordinary temperatures without the aid of heat or a flame.
- The slow, spontaneous oxidation of a compound by atmospheric oxygen at ambient temperatures, as occurs in drying oils, rancid fats, and deteriorating rubber.
"The rancidity of butter is caused by the autoxidation of its fats when exposed to air and light."
"Linseed oil hardens into a tough film through the process of autoxidation."
"Antioxidants such as vitamin E are added to foods specifically to slow the autoxidation of their lipids."
Rarely used in the plural; the noun is normally treated as uncountable since it names a process. A plural may occasionally appear when referring to distinct instances of the process in different substances.
"Different mechanisms of autoxidations were observed across the tested oils."
Every time cooking oil goes rancid or old rubber cracks, you're watching autoxidation — a slow-motion burn happening without any flame at all.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of autoxidation
Autoxidation is formed from the combining form "auto-", from Greek "autos" meaning "self", attached to "oxidation", a term built on "oxygene", the French name for oxygen coined by Lavoisier from Greek "oxys" (sharp, acid) and "-gen" (producing). The compound term arose in nineteenth-century chemical literature to describe oxidation that proceeds on its own, unaided by heat or ignition. Its relatives include the wider family of oxygen-derived terms such as oxide, dioxide, and antioxidant, all sharing the same Greek root for acid-sharpness.
Related word forms
How autoxidation is actually used
A technical term used chiefly in chemistry, food science, polymer science, and pharmacology. It carries no emotional connotation but often appears in contexts of spoilage, degradation, or preservation. The verb form "autoxidize" and the adjective "autoxidative" are used in the same technical registers.
Easily confused with autoxidation
Autoxidation is a slow, spontaneous reaction with oxygen at normal temperatures, whereas combustion is rapid oxidation accompanied by heat and light.