Abstract: The synthesis and characterization of the complexes between Eu(ClO₄)₃and bis (n-octasulfinyl) ethane and bis(phenylsulfinyl) ethane of high-melting (α) and low-melting (β) isomers are reported. The composition of compl exes of two isomers is rot the same. The complexes are Eu(ClO₄)₃·(α-BOSE)₃·2H₂O, Eu(ClO₄)₃·(β-ECSE)₄·2H₃O, Eu (ClO₄)₃·(α-BPhSE)₃and Eu(ClO₄)₃·β(-BhSE)₄·2H₂O.Eu(Ⅲ) ion are bonded to disulfoxide group and perchlorate ion via the oxygen atoms. The absorption bands of f-f transition of metal ion, charge transition of metal←ligand and electronic transition of ligand were observed. Emission spectra of complexes were also determined.