In the title compound, [Ni(2)(SO(4))(2)(C(13)H(8)N(4))(2)(H(2)O)(4)]·2H(2)O, the complete dimeric complex is generated by an inversion center. The Ni(II) atoms are octa-hedrally coordinated by two N atoms from one 1H-imidazo[4,5-f][1,10]phenanthroline (IP) ligand and two O atoms from two adjacent sulfate ions forming the equatorial plane, with two coordinated water mol-ecules in the axial sites. Both of the sulfate ions act as bidentate-bridging ligands connecting the two Ni(II) ions, thus generating a binuclear complex. In the crystal structure, O-H⋯O and O-H⋯N hydrogen bonds involving the coordinated and uncoordinated water mol-ecules and N-H⋯O links lead to the formation of a two-dimensional sheet structure developing parallel to (010). Weak π-π stacking inter-actions [centroid-centroid separation = 3.613 (2) Å] between the IP ligands also occur.