The hydrothermal reaction of PuO(2) with CH(2)(PO(3)H(2))(2) results in the formation of alpha-Pu[CH(2)(PO(3))(2)](H(2)O), beta-Pu[CH(2)(PO(3))(2)](H(2)O) (1), gamma-Pu[CH(2)(PO(3))(2)](H(2)O) (2), and Pu[CH(2)(PO(3))(2)](H(2)O).H(2)O (3) as crystalline compounds with blue, green, red, and very pale peach coloration, respectively. In all cases single crystal X-ray diffraction studies reveals Pu(4+) coordinated by [CH(2)(PO(3))(2)](4-) and water to yield PuO(7) units. The methylenediphosphonate anions bridge between these units to yield three-dimensional networks. Bond-valence parameters of R(o) = 2.068 and b = 0.385 have been derived for Pu(4+) using a combination of the data reported in this work with that available in crystallographic databases. UV-vis-NIR spectroscopic measurements demonstrate that despite the dramatic color differences all of the compounds contain Pu(4+), and that subtle changes in the visible region of the spectra account for different colors.