Formic Acid

Cas Number


Other Names

Carbonous acid

Formylic acid

Hydrogen carboxylic acid


Metacarbonoic acid

Oxocarbinic acid


The formula




Formic acid, systemically named methanoic acid, is the simplest carboxylic acid. The chemical formula is HCOOH or HCO2H. It is an important intermediate in chemical synthesis and occurs naturally, most notably in some ants.

Physical and Chemical Properties
Physical state and appearance Liquid
Odor Pungent. Penetrating. Benzaldehyde-like
Color Clear Colorless
PH (1% soln/water) Acidic
Boiling Point The lowest known value is 100°C (212°F) (Water). Weighted average: 100.67°C (213.2°F)
Flash point 69°C
Melting Point May start to solidify at 8.4°C (47.1°F) based on data for: Formic Acid
Specific Gravity Weighted average: 1.21 (Water = 1)
Vapor Pressure The highest known value is 4.7 kPa (@ 20°C) (Formic Acid). Weighted average: 4.6 kPa (@ 20°C)
Dispersion Properties See solubility in water, diethyl ether, acetone
Solubility Easily soluble in acetone. Soluble in cold water, hot water, diethyl ether
Formic Acid wt-% ≥99.0
Acetic Acid, mg/kg ≤50
Chloride, mg/kg ≤1
Evaporation residue, mg/kg ≤20
Sulphate, mg/kg ≤1
Fe, mg/kg ≤1
OtherHeavyMetalsEach, mg/kg ≤1

1. A major use of formic acid is as a preservative and antibacterial agent in livestock feed. In Europe, formic acid is applied on fresh hay or other silage to promote the fermentation of lactic acid and to suppress the formation of butyric acid; it also allows fermentation to occur quickly, and at a lower temperature, reducing the loss of nutritional value. Formic acid arrests certain decay processes and causes the feed to retain its nutritive value longer, and so it is widely used to preserve winter feed for cattle. In the poultry industry, it is sometimes added to feed to kill E. coli bacteria. Formic acid also used in the production of textiles and leather because of its acidic nature. It is also used as a coagulant in the production of rubber

2. Formic acid is also used in place of mineral acids for various cleaning products, such as limescale remover and toilet bowl cleaner. Some formate esters are artificial flavorings or perfumes

3. Beekeepers use formic acid as a miticide against the Tracheal (Acarapis woodi) mite and the Varroa mite

4. The use of formic acid in fuel cells is also under investigation

5. Formic acid is a source for a formyl group for example in the formylation of methylaniline to N-methylformanilide in toluene. In synthetic organic chemistry, formic acid is often used as a source of hydride ion. The Eschweiler-Clarke reaction and the Leuckart-Wallach reaction are examples of this application. It or more commonly its azeotrope with triethylamine, is also used as a source of hydrogen in transfer hydrogenation

6. Like acetic acid and trifluoroacetic acid, formic acid is commonly used as a volatile pH modifier in HPLC and capillary electrophoresis

7. As mentioned below, formic acid may serve as a convenient source of carbon monoxide by being readily decomposed by sulfuric acid