The title compound, C30H32O2N2, is formed from two units ofortho-hydroxynaphthaldehyde bridged with 1,8-diaminooctane. In the solid state, it exists as a double zwitterion. The N atoms are protonated and the C—O−bonds lengths are 1.265 (2) Å, with intramolecular N—H...O hydrogen bonds formingS(6) ring motifs. The molecule has twofold rotational symmetry, with the twofold axis bisecting the central –CH2—CH2– bond of the bridging octane chain. In the crystal, molecules are linked by N—H...O hydrogen bonds, forming chains propagating along the [-201] direction. The chains are linkedviaC—H...O hydrogen bonds, forming a supramolecular three-dimensional framework structure.