ABSTRACT: A new binuclear Gd(III) complex, [Gd2(L)6(Phen)2]·4H2O, was synthesized via the reaction of gadolinium(III) nitrate hexahydrate, 4-acetylphenoxyacetic acid (HL), NaOH, and 1,10-phenanthroline (Phen) in a solution of water-ethanol (v:v = 1:1). The Gd(III) complex was characterized using IR, UV-vis, TG-DSC, fluorescence, and single-crystal X-ray diffraction analyses. The results showed that the Gd(III) complex crystallizes in the triclinic system, space group P-1, and each Gd(III) ion was coordinated with two nitrogen atoms (N1, N2, or N1a, and N2a) from two Phen ligands and seven oxygen atoms (O1, O2, O7a, O9, O8, O8a, O10a, or O1a, O2a, O7, O8, O8a, O9a, and O10) from six L ligands, respectively, forming a nine-coordinated co