Two salts of 5-sulfosalicylic acid and 3-aminopyridine.

5-Sulfosalicylic acid (5-SSA) and 3-aminopyridine (3-APy) crystallize in the same solvent system, resulting in two kinds of 1:1 proton-transfer organic adduct, namely 3-aminopyridinium 3-carboxy-4-hydroxybenzenesulfonate monohydrate, C(5)H(7)N(2)(+).C(7)H(5)O(6)S(-).H(2)O or 3-APy.5-SSA.H(2)O, (I), and the anhydrous adduct, C(5)H(7)N(2)(+).C(7)H(5)O(6)S(-) or 3-APy.5-SSA, (II). Both compounds have extensively hydrogen-bonded three-dimensional layered polymer structures, with interlayer homo- and heterogeneous pi-pi interactions in (I) and (II), respectively.