Phenol or carbolic acid is a white crystalline solid, with a chemical formula of C6H5OH, a melting point of 43°C, and a boiling point of 182°C at the pressure of 1 atmosphere (or 101080 Pa). It is not a real alcohol, because the Hydroxy group is fixed on a unsaturated carbon, and it can be made from the partial oxidation of benzene, or by the cumene process or raschig process.

Despite the absence of a carboxyl group (-COOH), phenol is slightly acidic: the phenol molecule has weak tendencies to lose the H+ ion from the hydroxyl group due to the mesomeric effect.

Phenol has antiseptic properties, and was used by Sir Joseph Lister in his pioneering technique of antiseptic surgery, though the skin irritation caused by continual exposure to phenol eventually lead to the substitution of aseptic (germ-free) techniques in surgery.

It is used as a disinfectant and in the production of drugs, weedkillers, and synthetic resins - Bakelite, one of the first synthetic resins to be manufactured, is a polymer of phenol with formaldehyde. Exposure of the skin to concentrated phenol solutions causes chemical burns; in laboratories where it is used, it is usually recommended that polyethylene glycol solution is kept available for washing off splashes. Notwithstanding the effects of concentrated solutions, it is also used in cosmetic surgery as an exfoliant, to remove layers of dead skin.

Prisoners in Auschwitz I concentration camp hospital were often killed by phenol injections.

Dr. John H. Kellogg, who was later to be one of the founders of Kelloggs, advocated the application of "pure carbolic acid on the clitoris of females to prevent masturbation in children". (Plain facts for old and young, 1877).

see also phenols