Two uranyl nanotubules with elliptical cross sections were synthesized in high yield from complex and large oxoanions using hydrothermal reactions of uranyl salts with 1,4-benzenebisphosphonic acid or 4,4'-biphenylenbisphosphonic acid and Cs+ or Rb+ cations in the presence of hydrofluoric acid. Disordered Cs+/Rb+ cations and solvent molecules are present within and/or between the nanotubules. Ion-exchange experiments with A(2){(UO2)(2)F(PO3HC6H4C6H4PO3H) (PO3HC6H4C6H4PO3)}center dot 2H(2)O (A = Cs+, Rb+), revealed that A(+) cations can be exchanged for Ag+ ions. The uranyl phenyldiphosphonate nanotubules, Cs3.62H0.38[(UO2)(4){C6H4(PO2OH)(2)}(3){C6H4(PO3)(2)}F-2]center dot nH(2)O, show high stability and exceptional ion-exchange properties toward monovalent cations, as demonstrated by ion-exchange studies with selected cations, Na+, K+, Tl+, and Ag+. Studies on ion-exchanged single crystal using scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM/EDS) provide evidence for chemical zonation in Cs3.62H0.38[(UO2)(4){C6H4(PO2OH)(2)}(3){C6H4(PO3)(2)}F-2]center dot nH(2)O, as might be expected for exchange through a diffusion mechanism.