Two new organo-inorganic hybrid compounds, aluminum nitrilotris(methylene)trismonohydrogenphosphonate hydrate, Al[(HO3PCH2)3N]H2O, and tricopper(II) bis-nitrilobis(methylene)diphosphonate, Cu3[(O3PCH2)2NH2]2, have been synthesized. The crystal structures have been determined ab initio from powder diffraction data and refined by the Rietveld method. Al[(HO3PCH2)3N]H2O is monoclinic, space group P21/n, with a=12.1945(3) Å, b=9.1129(3) Å, c=8.5495(2) Å, β=94.317(2)°, Z=4, and the X-ray powder diffraction pattern has been refined to RwP=8.7%. Cu3[(O3PCH2)2NH2]2 is orthorhombic, space group Pbca, with a=16.1209(6) Å, b=9.4890(4) Å, c=9.4113(4) Å, Z=4 and its pattern was refined to RwP=13.5%. The crystal structure of aluminum phosphonate contains a close packing of inorganic chains, formed by alternating AlO6 octahedra and O3PC tetrahedra. These chains are covalently interconnected by the organic groups to give the 3D framework. The structure of copper phosphonate has two distinct copper environments, one a tetragonally elongated tetrahedron and the other a distorted square plane. These structural units are linked by the organic phosphonate. Thermal and infrared data are discussed.