The reaction of barium carbonate or hydroxide with oxydiacetic acid leads to the self-assembly of two barium oxydiacetate polymers in good yield: [Ba(oda) · H₂O]_n (1) and [Ba(Hoda)₂]_n (2). The products have been characterized by elemental analysis, IR, TGA and single crystal X-ray diffraction studies. The central barium atom in each mononuclear fragment is nine-coordinate in 1 and 10-coordinate in 2. These fragments are bridged by carboxylato groups in anti-anti conformation and through H-bonds bonding interactions forming complex 3D networks. The compound [Ba(oda) · H₂O]_n and [Ba(Hoda)₂]_n have been prepared and structurally characterized. The barium atom is nine-coordinate in the former and ten-coordinate in the latter, with the fragments connected by carboxylato groups in anti-anti conformation and through H-bonds bonding interactions forming complex 3D networks.