The crystal structure of the title compound, C(6)H(16)N(+)·C(19)H(18)O(2)PS(2) (-), consists of the dithio-phospho-nate anions and the triethyl-ammonium cations, which are linked by N-H⋯S hydrogen bonds and weak C-H⋯O hydrogen bonds. In the anion, the benzene ring is oriented with respect to the naphthalene ring system at a dihedral angle of 24.92 (5)°. In the crystal, weak C-H⋯π inter-actions also occur.