Crystal growth and structure of a new organic cation diphosphate with formula (2-C2H5C6H4NH3)(2)H2P2O7 are reported. This compound is monoclinic C2/C With the following unit-cell parameters: a = 28.400(8), b = 4.586(2), c = 15.609(1) Angstrom, beta = 101.75(1)degrees Z = 4, V = 1990.3(8) Angstrom (3) and D-x = 1.403 g.cm(-3). Crystal structure has been determined and refined to R = 0.055, using 3223 independent reflections. The atomic arrangement is build up by infinite ribbons of (H2P2O72-) anions spreading parallel to the b axis. These ribbons are themselves interconnected by the organic (2-C2H5C6H4NH3)(+) groups to form a layer in a two-dimensional way. Compound characterization by IR absorption and TA are described too.