1-Ammonionaphthalene-2-sulfonate

In the molecule of the zwitterionic title compound, C10H9NO3S, an intramolecular N—H...O hydrogen bond results in the formation of an almost planar six-membered ring (r.m.s daviation = 0.0150 ), which is oriented at a dihedral angle of 1.63 (3)° with respect to the naphthalene ring system. In the crystal structure, intermolecular N—H...O hydrogen bonds link the molecules into a two-dimensional network.