Descripción: The title complex, aqua(2,2′-bipyridy-N,N′(3-thiapentanedioate-O,S,O′)zinc(II) tetrahydrate, [Zn(C4H4-O4S)(C10H8N 2)(H2O)].4H2O, is mononuclear with a coordination sphere consisting of one S, two N and three O atoms. The Zn atom is linked to a tridentate thiodiacetate ligand, a bidentate 2,2′-bipyridine ligand and an aqua ligand resulting in a slightly distorted octahedral coordination geometry. The molecular units are linked together in the crystal by an extensive hydrogen-bonding network and by intermolecular S⋯S interactions.