Crystals of silver(II) bis(pyridine-2,6-dicarboxylate) monohydrate are orthorhombic, space group Pnna, with a= 7·874(5), b= 10·942(7), c= 17·734(12)Å, and Z= 4. The intensities of 761 reflections above background were collected by counter methods and the structure has been refined to a conventional R of 0·09. The molecule has imposed two-fold symmetry. The silver atom is six-co-ordinate being bonded to the nitrogen and two oxygen atoms from each of the tridentate ligand molecules. The two ligands co-ordinate in a strikingly different manner, the co-ordination best being described as from anionic (A) and neutral (B) ligand molecules. For ligand (A), the silver atom forms single bonds to the nitrogen [2·09(2)Å] and to the two negatively charged (and crystallographically equivalent) oxygen atoms [2·20(1)Å]. For ligand (B), the silver atoms is bonded less strongly to the nitrogen [2·21 (2)Å] and to the two ketonic oxygen atoms [2·53(1)Å]. The electronic absorption spectra of the monohydrate and tetrahydrate are very similar and quite unlike those of silver(II) species in square-planar or tetragonally distorted octahedral environments.