Poly[diaqua-(μ(2)-5-carboxy-pyridine-3-carboxyl-ato-κN:O)hemi(μ(2)-oxalato-κO,O:O,O)(μ(4)-pyridine-3,5-dicarboxyl-ato-κN:O:O:O)silver(I)terbium(III)].

In the title coordination polymer, [AgTb(C(7)H(3)NO(4))(C(7)H(4)NO(4))(C(2)O(4))(0.5)(H(2)O)(2)](n), the Tb(III) ion is eight-coordinated by three O atoms from three different pydc (H(2)pydc = pyridine-3,5-dicarboxylic acid) ligands, one O atom from one Hpydc ligand, two O atoms from one oxalate ligand and two water mol-ecules in a distorted square-anti-prismatic geometry. The Ag(I) ion is coordinated in an almost linear fashion by two pyridyl N atoms from one pydc and one Hpydc ligand and has weak inter-actions with two carboxyl-ate O atoms. The carboxyl-ate groups of pydc and Hpydc ligands link Tb centers, forming a one-dimensional chain. The oxalate adopts a tetra-dentate bis-chelating coordination mode, connecting the chains into a two-dimensional layer. These layers are further assembled via [Ag(pydc)(Hpydc)] pillars and O-H⋯O and C-H⋯O hydrogen bonds into a three-dimensional coordination framework.