Formic acid (HCOOH) is naturally-occurring, flammable, corrosive, organic, and the simplest carboxylic acid. Used as a hydride ion source in synthetic organic chemistry, a mobile phase component in HPLC, a preservative/antibacterial agent in agriculture, etc.

Formic or methanoic acid (CAS: 64-18-6; PubChem ID: 284) is a colorless organic acid with the formula HCOOH. At ambient temperatures, it has a strong, penetrating odor, like acetic acid. Used in chemical synthesis as an intermediate, this simple carboxylic acid is miscible in water and most organic solvents and is somewhat hydrocarbon-soluble.

Formic acid occurs naturally in the venom of some ants and bees. Formate, the conjugate base of formic acid, also occurs naturally in bodily fluids following methanol poisoning.

Formic acid is a source of hydride ion in synthetic organic chemistry, as in the Eschweiler-Clarke and Leuckart-Wallach reactions. It is also a useful component of the mobile phase in reversed-phase high-performance liquid chromatography (RP-HPLC) for peptides, proteins, and intact viruses.

Although formic acid is easily metabolized and eliminated, it can have toxic effects. Methanol metabolism produces formic acid and formaldehyde, which are responsible for the optic nerve damage that results from methanol poisoning. Chronic exposure in humans may cause kidney damage and skin allergies in some people.

In diluted forms, formic acid and formate esters are used as artificial flavorings and perfume additives. In higher concentrations, formic acid is flammable, and skin and eye contact with concentrated liquid or vapors is dangerous.

In agriculture, formic acid is used as a preservative and antibacterial agent and by beekeepers to kill mites. It is useful in leather tanning, textile dyeing and finishing, and in rubber production. Formic acid replaces mineral acids in limescale removers and other cleaning products.