Crystals of 2(2-ammonium ethyl ammonium) ethanol monohydrogemnonophosphate monohydrate: (C4H14N2O)HPO4-H2O abbreviated as AEEHP, were prepared and grown at room temperature. The AEEHP crystallizes in the monoclinic system with the P2(1)/a space group. Its unit cell dimensions are: a = 4.8236(2), b = 28.429(2), c = 7.0711(6) angstrom, and beta = 94.881(4)degrees with V = 966.14(11) angstrom(3) and Z = 4. The structure of this compound was determined by using X-ray data collection on single-crystal. The AEEHP structure is built up from infinite inorganic HPO42- chains parallel to the a-axis, alternating with infinite chains of H2O molecules. These chains are interconnected by organic groups so as to build a three dimensional arrangement. In the present work, we describe the crystal structure, thermal behavior and IR analysis of this new compound. (c) 2004 Elsevier Ltd. All rights reserved.