Two new metal carboxyphosphonates with 2D supramolecular and layered structures based on 4-HOOCC 6 H 4 CH 2 PO(OH) (OC 2 H 5 ) (H 2 L′), namely, [Cd(H 2 L) 2 (H 2 O) 2 ] (1) and [Ag(H 2 L)] (2) [H 3 L = 4-HOOCC 6 H 4 CH 2 PO(OH) 2 ], have been synthesized under hydrothermal conditions. For compound 1, {CdO 6 } octahedra and {CPO 3 } tetrahedra are interconnected into a 1D chain via corner–sharing along the a–axis. Then the adjacent chains are further connected through hydrogen bonds of the carboxyl acid groups of ligands into a 2D supramolecular structure in the ac plane. Compound 2 features a 2D layered structure. Every two {AgO 3 } polyhedra and two {CPO 3 } tetrahedra are interconnected into a unit via corner–sharing. Such untis are further connected through carboxyphosphonate ligands to form a 2D layered structure. There is a 40–atom window in compound 2. The luminescent properties of compounds 1 and 2 have also been studied.