In the crystal structure of the mononuclear title compound, (C(5)H(8)N(3))(2)[Co(C(6)H(2)N(2)O(4))(2)(H(2)O)(2)]center dot 6H(2)O or (ampymH)(2)[Co( pyzdc)(2)(H(2)O)(2)]center dot 6H(2)O (ampym = 2-amino-4-methyl pyrimidine, pyzdcH(2) = pyrazine-2,3-dicarboxylic acid), the Co(II) ion is hexacoordinated by two (pyzdc)(2-) groups in the equatorial plane and two water molecules in axial positions, giving an N(2)CoO(4) bound set. The (pyzdc)(2-) anion acts as a bidentate ligand through one carboxylate group O atom and pyrazine ring N atom. There are diverse N-H center dot center dot center dot O and O-H center dot center dot center dot O and O-H center dot center dot center dot N hydrogen-bonding interactions, which lead to the formation of a three-dimensional supramolecular architecture. Off-set or slipped pi-pi stacking interactions are also observed between adjacent pyrimidine rings with face-to-face distances of 3.6337 (9) angstrom.