Abstract 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-CH 3C 6H 4NH 3) 6P 6O 18·8H 2O. 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) Å, and β = 97.53(4)°. 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 P 6O 18 ring anions and water molecules spread parallel to the plane (010). Between these layers are located the organic groups that form hydrogen bonds with P 6O 18 ring oxygens. Geometrical characteristics of the hydrogen bonds are described.