The new mixed-ligand complex of [Tl(Ph2phen)Cl3(DMSO)] (1) is obtained from the reaction of TlCl3*4H2O with 4,7-diphenyl-1,10-phenanthroline (Ph2phen) in a methanol solution. Suitable crystals of 1 are obtained for the X-ray diffraction measurement by methanol diffusion into a DMSO solution. This complex is characterized by spectral methods (IR, UV-Vis, 1H NMR, and luminescence), elemental analysis, thermal analysis (TG, DTA), and single crystal X-ray diffraction.