The first dinuclear platinum complex with a silsesquioxanate ligand {[Pt(Ph)(PEt3)2]2O11Si7(c-C5H9)7(OH)} was synthesized by reaction of incompletely condensed silsesquioxane, (c-C5H9)7Si7O9(OH)3 with trans-PtI(Ph)(PEt3)2. Multinuclear (1H, 13C, 29Si, and 31P) NMR data clearly show two unequivalent platinum moieties (Pt(Ph)(PEt3)2) bridged by bulky silsesquioxanate ligand. DFT calculations were performed to analyse the molecular structure and NMR properties of the new platinum complex.