The asymmetric unit of the title polymer, {[Na(4)(C(15)H(14)N(2)O(4))(2)]·7.5H(2)O}(n), contains two 2-[(3,5-dimethyl-1H-pyrazol-1-yl)(phen-yl)meth-yl]propane-dioate (ppmp) anions, eight water mol-ecules (one located on a twofold rotation axis) and five sodium cations (one located on an inversion center and the other one located on a twofold rotation axis). The carboxyl-ate groups of the ppmp anions and the water mol-ecules bridge the Na cations, forming a two-dimensional polymeric structure. In the structure there are two types of coordination environment around the metal cations: one Na cation is coordinated by five O atoms in a distorted square-pyramidal geometry while the other four Na cations are coordinated by six O atoms in a distorted octa-hedral geometry. Extensive O-H⋯O and O-H⋯N hydrogen bonding is present in the crystal structure. The H atoms of one methyl group of the ppmp anion are disordered equally over two positions.