catena-Poly[[(tetra-aqua-cadmium)-μ-4,4'-bipyridine-κ(2)N:N'] 4-hy-droxy-3-sulfonato-benzoate monohydrate].

The two independent Cd(II) atoms in the polymeric title compound, [Cd(C(10)H(8)N(2))(H(2)O)(4)](C(7)H(4)O(6)S)·H(2)O, lie on twofold rotation axes, and each is coordinated by four water mol-ecules and the N atoms of two 4,4'-bipyridine mol-ecules in an octa-hedral geometry. Bridging gives rise to chains along [101] and [-101]. The 4-hy-droxy-3-sulfonato-benzoate dianions are not connected to the Cd(II) atoms, but form hydrogen bonds to the coordinated water mol-ecules as well as the lattice water mol-ecule, generating a three-dimensional network.