The Co(II) atom in the title complex, {[Co(C(10)H(8)N(2))(H(2)O)(4)](C(8)H(4)O(4))}(n), is coordinated by two N atoms of two bipyridine ligands and four O atoms of four water mol-ecules in an octahedral geometry. The one-dimensional [Co(C(10)H(8)N(2))(H(2)O)(4)](2+) cation chain is further extended into a supra-molecular network via O-H⋯O hydrogen-bond inter-actions. The Co atom lies on a twofold rotation axis; another twofold rotation axis passes through the carboxylate carbon atoms and the attached ring C atoms.