In the title compound, C(2)H(10)N(2) (2+)·0.5(C(2)O(4))(2-)·NCS(-), the ethyl-enediaminium dication adopts a (+)-synclinal conformation with an N-C-C-N torsion angle of 62.64 (15)°. The oxalate dianion lies across an inversion centre. In the crystal structure, the ions are linked through N-H⋯N, N-H⋯O and C-H⋯S hydrogen bonds, leading to the formation of a three-dimensional network.