The hydro-thermal reaction of benzene-1,4-dicarboxylic acid and 4,4'-trimethyl-ene dipiperidine leads to the formation of the title compound, C(13)H(28)N(2) (2+)·C(8)H(4)O(4) (2-). The anion is located on a center of inversion whereas the cation is positioned on a twofold rotation axis. In the crystal structure, the anions and cations are linked by N-H⋯O and N-H⋯(O,O) hydrogen bonds.