Abstract : The reaction of Cu(ClO4)2 * 6H2O with t-BuP(O)(OH)2 and 3,5-(CF3)2PzH in the presence of triethylamine afforded the dodecanuclear cage {[Et3NH]2[Cu12(μ-3,5-(CF3)2Pz)6(μ3-OH)6(μ-OH)3(μ3-t-BuPO3)2(μ6-t-BuPO3)3][t-BuPO2OH]- [C6H5CH3]2} (2). The molecular structure of this cage revealed that it possesses a barrel-shaped architechture. The cage structure is built by the cumulative coordination action of phosphonate, hydroxide, and pyrazolyl ligands. A similar reaction involving Cu(NO3)2 * 3H2O, t-BuP(O)(OH)2, 3,5-dimethylpyrazole, and triethylamine afforded another dodecanuclear cage [Cu12(μ-DMPz)8(η1-DMPzH)2(μ4-O)2(μ3-OH)4(μ3-t-BuPO3)4] * 3MeOH (3). The latter is crownshaped and is built by the coordination of pyrazole, pyrazolyl, phosphonate, hydroxide, oxide, and methanol ligands. Both of the dodecanuclear cages are efficient nucleases in the presence of magnesium monoperoxyphthalate.