Crystals of a new organic compound, the isonicotinic acid hydrazide dihydrogendiphosphate, (C6H9N3O)H2P2O7 (denoted INHDP) were prepared and grown at room temperature. The INHDP crystallizes in the triclinic system with the P (1) over bar space group. Its unit cell dimensions are: a = 7.316(3) angstrom, b = 7.783(3) angstrom, c = 10.802(4) angstrom, alpha = 82.41(3)degrees, beta = 75.19(3)degrees, gamma = 72.57(3)degrees, with V = 566.3(4) angstrom(3) and Z = 2. Crystal structure has been determined and refined to a reliability R factor of 0.0389. The atomic arrangement can be described as inorganic infinite ribbons of H2P2O72- anions spreading parallel to the b-axis. These ribbons are themselves interconnected by the organic (C6H9N3O)(+) cations so as to build a three dimensional arrangement. In the present work, we describe the crystal structure, thermal behaviour and IR analysis of this new compound. (C) 2006 Elsevier Ltd. All rights reserved.