Chemical preparation, crystal structure and thermal behaviour are given for a new organic-cation cyclohexaphosphate: ((C6H5CH2)(2)NH2)(6)P6O18.6H(2)O). This compound is monoclinic P2(1)/m with the following unit-cell parameters: a = 10.752(4) Angstrom, b = 24.029(9) Angstrom, c = 13.348(4) Angstrom, beta = 106.36(3)degrees and Z = 2. Crystal structure has been determined and refined to R = 0.041 using 2961 independent reflections. This structure can be described as a stacking of ribbons spreading parallel to the a-direction, formed by the P6O18 ring anions and the water molecules. The ribbons are interconnected by the dibenzylammonium proups. (C) 2004 Elsevier Ltd. All rights reserved.