4-[(4-Amino-phen-yl)sulfon-yl]aniline-3,5-dinitro-benzoic acid (1/1).

The title compound, C(7)H(4)N(2)O(6)·C(12)H(12)N(2)O(2)S, is a 1:1 cocrystal of the drug dapsone with 3,5-dinitro-benzoic acid. The dihedral angle between the two aromatic rings of the dapsone mol-ecule is 75.4 (2)°, and the dihedral angles between these rings and that of the 3,5-dinitro-benzoic acid are 64.5 (2) and 68.4 (2)°. A strong inter-molecular carb-oxy-lic acid O-H⋯N(amine) hydrogen bond is found, together with inter-molecular amine N-H⋯O hydrogen-bonding associations with carboxyl, nitro and sulfone O-atom acceptors. In addition, weak π-π inter-actions between one of the dapsone benzene rings and the 3,5-dinitro-benzoic acid ring [ring centroid separation = 3.774 (2) Å] results in a two-dimensional network structure.