In the title compound, [Co(C(12)H(9)N(2)O(2)S)(2)(H(2)O)(4)], the Co(II) ion, lying on an inversion center, has an octa-hedral coordination involving two N atoms of two 4-(pyrazin-2-ylsulf-anylmeth-yl)benzoate ligands and four water mol-ecules. In the crystal, O-H⋯O hydrogen bonds between the coordinated water mol-ecules and uncoordinated carboxyl-ate O atoms, and weak π-π inter-actions [centroid-centroid distance = 4.105 (2) Å] between the benzene and pyrazine rings lead to a three-dimensional supra-molecular network.