A new layered inorganic-organic hybrid aluminum phosphate-oxalate [H3N(CH2)(4)NH3](2)[Al-4(C2O4)(H2PO4)(2)(PO4)(4)]center dot 4[H2O](AlPO-CJ25) has been synthesized hydrothermally, by using 1,4-diaminobutane (DAB) as structure-directing agent. The structure has been solved by single-crystal X-ray diffraction analysis and further characterized by IR, P-31 MAS NMR, TG-DTA as well as compositional analyses. Crystal data: the triclinic space group P-1, a = 8.0484(7) angstrom, b = 8.8608(8) angstrom, c = 13.2224(11) angstrom, a = 80.830(6)degrees, beta = 74.965(5)degrees, beta = 78.782(6)degrees, Z = 2, R-t[I > 2 sigma(I)] = 0.0511 and wR(2(all data)) = 0.1423. The alternation of AlO4 tetrahedra and PO4 tetrahedra gives rise to the four-membered corner-sharing chains, which are interconnected through AlO6 octahedra to form the layered structure with 4,6-net sheet. Interestingly, oxalate ions are bis-bidentately bonded by participating in the coordination of AlO6, and bridging the adjacent AlO6 octahedra. The layers are held with each other through strong H-bondings between the terminal oxygens. The organic ammonium cations and water molecules are located in the large cavities between the interlayer regions. (c) 2005 Elsevier Inc. All rights reserved.