The novel title compound, [Ba(3)(C(3)H(5)Cl(2)O(6)P(2))(2)(C(3)H(6)O)(H(2)O)(4)](n), has a polymeric two-dimensional network structure which lies parallel to the (10-1) plane. The asymmetric unit consists of three independent Ba(2+) ions, two of them eight-coordinated and the third nine-coordinated, and two independent ethyl (dichloromethylene)diphosphonate(3-) ligands, one acetone ligand and four aqua ligands. The coordination environments around the BaO(8) polyhedra are best described as bicapped trigonal prismatic, while the BaO(9) polyhedron is in a distorted tricapped trigonal prismatic geometry. The two diphosphonate ligands adopt different coordination modes. Both ligands chelate three metal cations, but one is coordinated to six metal cations in total and forms two six-membered and one four-membered chelate ring, while the other is coordinated to five metal cations in total and forms one six-membered and two four-membered chelate rings, the fifth unsubstituted O atom remaining uncoordinated.