In catena-poly[[[triaquacadmium(II)]-micro-acetylenedicarboxylato-kappa(4)O,O':O",O"'] hydrate], [[Cd(C(4)O(4))(H(2)O)(3)].H(2)O](n), the Cd(II) atom is coordinated by two bidentate carboxylate groups and three water molecules, thus forming a sevenfold coordination polyhedron with all atoms located on general sites. These polyhedra are connected by the bifunctional acetylenedicarboxylate ligands, forming zigzag chains running parallel to [120]. Hydrogen bonds, which involve the non-coordinated water molecule, connect these chains to form a three-dimensional framework.