The title compound, (C9H8NO)[CuCl3(C7H5NO4)]·2H2O, was synthesized by reacting CuII acetate, 8-hy­droxy­quinoline, and pyridine-2,6-di­carb­oxy­lic acid in dilute hydro­chloric acid in a 1:1:1 molar ratio. The Cu(II) atom exhibits a distorted octa­hedral geometry coordinated by the H2pydc ligand and chloride atoms. In the crystal structure, various hydrogen bonds and weak inter­actions lead to the formation of a three-dimensional network.

The asymmetric unit of the title compound consists of two independent ion pairs of 4-(di­methyl­amino)­pyridin-1-ium quinolin-8-ol-5-sulfonate (HDMAP+·HqSA−) and neutral N,N-di­methyl­pyridin-4-amine (DMAP), forming a 1:1:1 cation:anion:neutral mol­ecule co-crystal. The compound has a layered structure, including cation layers of HDMAP+ with DMAP and anion layers of HqSA− in the crystal. The cation and anion layers are linked by inter­molecular C—H⋯O hydrogen bonds and C—H⋯π inter­actions.

The crystal structure of the organic salt features classical hydrogen-bonding inter­actions involving the 8-hy­droxy­quinolinium cation, the naphthalene-1,5-di­sulfonate anion and the two water mol­ecules of crystallization.