A novel and simple approach to the synthesis of a new organic-inorganic 4C(3)H(5)N(3)O(3)(2+)center dot 2C(3)H(4)N(3)O(3)(+)center dot 5HPO(4)(2-)center dot 4H(2)O resulted from the reaction of melamine and phosphoric acid in methanol. It was identified by means of the single crystal X-ray diffraction and characterized using different physicochemical studies to gain deeper insight in its structure. The determination of the crystal structure showed that the compound crystallizes in monoclinic system with the space group P2(1), lattice parameters a = 11.3061 angstrom, b = 20.9911)angstrom, c = 12.2711 angstrom. The UV-Vis shows a good transmittance in the visible range, with an absorption threshold at 255 nm. The thermal behavior divulges a good thermal stability up to 230 degrees C.