Bis(2-amino-4-methyl-pyrimidin-1-ium) hexa-aqua-cobalt(II) disulfate dihydrate.

In the title hydrated mixed-cation salt, (C(5)H(8)N(3))(2)[Co(H(2)O)(6)](SO(4))(2)·2H(2)O, the complete octa-hedral hexa-aqua complex cation is generated by crystallographic inversion symmetry. In the crystal, the components are linked by O-H⋯O and N-H⋯O hydrogen bonds, the latter, involving pyrimidinium cations and sulfate anions, generating R(2) (2)(8) loops. These, together with π-π inter-actions between centrosymmetrically related pyrimidinium cations [centroid-centroid separation = 3.5460 (8) Å], lead to the formation of a three-dimensional network.