The tri-cationic shell gallium complex [Ga(CH₂(P(O)Ph) ₂)₃]³⁺ containing three neutral diphosphate oxide ligands has been synthesized and structurally characterized by using X-ray crystallography, mass spectrometry, and ¹H, ¹³C, ³¹P, and ⁷¹Ga NMR spectroscopy. The ligands form three equivalent six-membered chelate cycles to give an idealized octahedral environment around the Ga³⁺ ion. This compound is the first example of a mononuclear homoleptic octahedral structure formed by neutral phosphine oxide ligands in the chemistry of the 13 group elements in the +3 oxidation state.