In the title compound, [Co(C(9)H(6)N(3)O(3)S)(2)(H(2)O)(4)]·H(2)O, the two 2-{[5-(pyridin-4-yl)-1,3,4-oxadiazol-2-yl]sulfan-yl}acetate ligands are monodentate. One coordinates the metal atom via the pyridyl N atom whereas the other coordinates via the carboxyl-ate O atom. The Co(II) atom adopts a slightly distorted octa-hedral coordination geometry with four O atoms of the coordinated water mol-ecules located in the equatorial plane and the N and O atoms of the two POA ligands in axial positions. In the crystal, the components are connected through O-H⋯O and O-H⋯N hydrogen bonds into a three-dimensional framework.