Colorless plate-like crystals (AlPO-1,2DAP) crystallize from a clear 'AlPO 4 -1,2-diaminopropane' reaction system. The results of elemental, thermal and FTIR analyses give the following chemical formula: (NH 4 + )(1,2-H 2 DAP) 2 + (AlP 2 O 8 ) 3 - , confirmed also by single crystal structure determination. The X-ray diffraction data collected at 150K reveal the space group Pc2 1 n with a=8.2788(2), b=16.7882(3), c=8.6608(2)Å, and V=1203.73(5)Å 3 . The AlPO-1,2DAP has a chain structure related to the aluminophosphate AlPO-enA structure. Two occluded cations, NH 4 + and doubly protonated diamine, balance the negative charge and interact with the chain oxygen atoms via hydrogen bond network.