Hydroxide or hydroxyl ion is a diatomic anion with chemical formula OH−. It consists of an oxygen and hydrogen atom held together by a covalent bond, and carries a negative electric charge.
It is an important but usually
minor constituent of water. It functions as a
base, a
ligand, a
nucleophile and a
catalyst. The hydroxide ion forms
salts, some of which
dissociate in aqueous solution, liberating solvated hydroxide ions.
Hydroxide ion and
hydroxyl group are nucleophiles and can act as a catalyst in organic chemistry.