A mixed hydroxo/oxo plutonium(IV) carboxylate resulting from the hydrolysis and condensation of Pu-IV in an acidic aqueous solution has been isolated. The structure of Li-6[Pu-6(OH)(4)O-4(H2O)(6)(HGly)(12)]Cl-18 center dot 10.5H(2)O (1) consists of a cationic [Pu-6(OH)(4)O-4](12+) core that is decorated by glycine ligands. The synthesis, structure, and characterization of the hexanuclear unit, which represents the first example of a Pu-IV polynuclear complex containing both hydroxo- and oxo-bridging ligands, are described herein.