Preparation and complete structural characterization by X-ray diffraction (XRD), IR absorption, thermogravimetric and differential thermal analysis (TG-DTA), and mass angle spinning (MAS) NMR spectroscopy are given for a new cyclohexaphosphate, (p-CH3C6H4NH3)(6)P6O18. 8H(2)O. This compound is monoclinic in space group P2(1)/c, with Z = 2 and unit-cell parameters a = 10.695(6), b = 24.952(8), c = 11.163(4) Angstrom, and beta = 97.53(4)degrees. The crystal structure was solved and refined down to R = 0.036, using 4168 independent reflections. The atomic arrangement can be described as layer organization. Layers built by P6O18 ring anions and water molecules spread parallel to the plane (010). Between these layers are located the organic groups that form hydrogen bonds with P6O18 ring oxygens. Geometrical characteristics of the hydrogen bonds are described.