The title complex, [Fe(2)O(SO(4))(2)(C(12)H(8)N(2))(4)]·8H(2)O, contains two unique Fe(III) cations, one oxide anion, four 1,10-phenanthroline (phen) ligands, two coordinated sulfate anions and eight lattice water mol-ecules. Each Fe(III) ion has an approximate octa-hedral geometry, coordinated by four N atoms from two phen mol-ecules, two O atoms from oxide and sulfate anions, respectively. The parallel phen mol-ecules form two-dimensional supermolecules through π-π stacking inter-actions [centroid-centroid distances = 3.684 (3), 3.711 (3), 3.790 (3), 3.847 (3), 3.746 (3), 3.732 (3) and 3.729 (3) Å]. This architecture is further stabilized by O-H⋯O hydrogen bonds involving the lattice water mol-ecules and sulfate O atoms.