In the title compound, {[Co(C(10)H(14)N(4))(2)(H(2)O)(2)]Cl(2)·4H(2)O}(n), the Co(II) atom and the mid-point of the 1,1'-butane-1,4-diyl-diimidazole ligands lie on inversion centers. The Co(II) atom is six-coordinated in a slightly distorted octa-hedral environment by four N atoms from four different ligands and by two O atoms from the water mol-ecules. The Co(II) atoms are bridged by the ligands into a (4,4) net. Adjacent nets are linked to the chloride anions and uncoordinated water mol-ecules via O-H⋯Cl and O-H⋯O hydrogen bonds, generating a three-dimensional supra-molecular structure.