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, C₅H₇N₂⁺·C₇H₅O₆S⁻·H₂O or 3-APy·5-SSA·H₂O, (I), and the anhydrous adduct, C₅H₇N₂⁺·C₇H₅O₆S⁻ or 3-APy·5-SSA, (II). Both compounds have extensively hydrogen-bonded three-dimensional layered polymer structures, with inter­layer homo- and heterogeneous π–π inter­actions in (I) and (II), respectively.