The title compound, [Nd(C(8)H(6)NO(4))(C(2)O(4))(H(2)O)](n), is a layer-like coordination polymer. The Nd(III) ion is coordinated by four carboxyl-ate O atoms from three bridging 5-aza-nium-yl-isophthalate (Haip) ligands, four carboxyl-ate O atoms from two oxalate (ox) anions and one ligated water mol-ecule in a tricapped trigonal-prismatic geometry. The Haip anion acts as a μ(3)-bridge, connecting three Nd(III) ions through two carboxyl-ate groups; the ox anion adopts a bis-bidentate-bridging mode, linking two Nd(III) ions. The layer framework is further extended to a three-dimensional supra-molecular structure through N-H⋯O and O-H⋯O hydrogen bonds.