In the centrosymmetric dinuclear title compound, [Co(2)(SO(4))(2)(C(13)H(8)N(4))(2)(H(2)O)(4)]·2H(2)O, the Co(II) atom is coord-in-ated by two N atoms from two 1H-imidazo[4,5-f][1,10]phenanthroline ligands, two O atoms from two sulfate anions and two O atoms from water mol-ecules in a distorted octa-hedral geometry. The Co⋯Co separation is 5.1167 (7) Å. The coordinated and uncoordinated water mol-ecules engage in N-H⋯O and O-H⋯O hydrogen-bonding inter-actions.