Benzoic acid ÉnËzoÊ.ɪk/ is a white (or colorless) solid organic compound with the formula C6H5COOH, whose structure consists of a benzene ring (C6H6) with a carboxyl (C(=O)OH) substituent. The benzoyl group is often abbreviated "Bz" (not to be confused with "Bn" which is used for benzyl), thus benzoic acid is also denoted as BzOH, since the benzoyl group has the formula C6H5CO. It is the simplest aromatic carboxylic acid. The name is derived from gum benzoin, which was for a long time its only source.