Ball-and-stick model of the hyroxyl group.
The monovalent functional group –OH found, for example, in alcohols and phenols. It consists of a hydrogen atom and a oxygen atom bound together by a covalent bond. In alcohols, the hydroxyl group is attached to a carbon atom in a hydrocarbon chain, while in phenols the hydroxyl group is attached directly to the hydrocarbon ring. It should not be confused with the hydroxide ion, OH-.