Anthracene-9-carboxylic acid, C15H10O2, was found to crystallize in the centrosymmetric space group P2(1)/n. The hydrogen bonding is of the cyclic-dimer type about a center of symmetry. The carboxyl O atoms are ordered, as is the carboxyl H atom. The anthracene core is almost planar and shows good agreement with the anthracene core of anthracene-1, 8-dicarboxylic acid. The carboxyl group plane makes a dihedral angle of 54.87 (6) degrees with the best-fit anthracene core plane.