Structural properties of the 2,4,6-triaminopyridinium dihydrogendiphosphate dihydrate are discussed on the basis of an X-ray structure investigation. (C4H8N5)(2)H2P2O7 center dot 2H(2)O is monoclinic, C2/c, with a = 10.414(1)angstrom, b = 13.365(1)angstrom, c = 13.736(2)angstrom, beta = 98.39(4)degrees, and Z = 4. The structure has been solved by a direct method and refined to a reliability R factor of 0.0375 (R-w = 0.0961) using 2751 independent reflections. The structural arrangement can be described as inorganic infinite ribbons, [H2P2O7(H2O)(2)](n)(2n), spreading along the c direction; the organic groups, [C4H8N5](+), link the precedent ribbons, via their hydrogen bonds, to form a three-dimensional network. The present work, deals with crystal structure, thermal behavior and IR analysis of this new compound. (C) 2008 Elsevier Ltd. All rights reserved.