2-Naphthoic acid is an organic compound of the formula C<sub>10</sub>H<sub>7</sub>CO<sub>2</sub>H. It is one of two isomeric carboxylic acid derivatives of naphthalene, the other one being 1-naphthoic acid. It can be prepared by carboxylation of 1-chloronaphthalene. Its pK<sub>a</sub> is 4.2. The name of carboxylate anion, the conjugate base of the acid, is 2-naphthoate; the name of the related acyl group is 2-naphthoyl.