In the cation of the title salt, C(6)H(7)N(2)O(2) (+)·C(7)H(7)O(3)S(-), the benzene ring makes a dihedral angle of 10.2 (2)° with the nitro group. In the crystal, the cations and anions are linked by weak N-H⋯O hydrogen bonds, forming a layer parallel to the ac plane. A weak C-H⋯O inter-action and π-π inter-actions [centroid-centroid distances of 3.738 (3) and 3.748 (3) Å] also observed within the layer.