Pyrazine and 5-sulfosalicylic acid crystallize from a methanol solution containing water as the title salt, C(4)H(6)N(2) (2+)·2C(7)H(5)O(6)S(-)·2H(2)O. The pyrazine-diium cation sits on an inversion center. The component ions and water mol-ecules are linked by inter-molecular O-H⋯O, N-H⋯O and C-H⋯O hydrogen bonds into layers running parallel to the (10) plane.