The known xenon-binding (+/-)-cryptophane-111 (1) has been functionalized with six [(eta(5)-C5Me5)Ru-II](+) ([Cp*Ru](+)) moieties to give, in 89% yield, the first water-soluble cryptophane-111 derivative, namely [(CP*Ru)(6)1]Cl-6 ([2]Cl-6). [2]Cl-6 exhibits a very high affinity for xenon in water, with a binding constant of 2.9(2) x 10(4) M-1 as measured by hyperpolarized Xe-129 NMR spectroscopy. The Xe-129 NMR chemical shift of the aqueous Xe@[2](6+) species (308 ppm) resonates over 275 ppm downfield of the parent Xe@1 species in (CDCl2)(2) and greatly broadens the practical Xe-129 NMR chemical shift range made available by xenon-binding molecular hosts. Single crystal structures of [2][CF3SO3](6)center dot xsolvent and 0.75H(2)O@1 center dot 2CHCl(3) reveal the ability of the cryptophane-111 core to adapt its conformation to guests.