In the title complex, {[Na(C(7)H(7)N(2)O(4))(H(2)O)(2)]·H(2)O}(n), the Na(I) atom exhibits a distorted octa-hedral geometry and is six-coordinated in an NO(5) environment. The equatorial plane is defined by three O atoms and one N atom from two distinct 5-carb-oxy-2-ethyl-1H-imidazole-4-carboxyl-ate (H(2)EIDC) ligands and one coordinated water mol-ecule, and the apical sites are occupied by one carboxyl O atom from one H(2)EIDC ligand and one O atom from the other coordinated water mol-ecule. The Na(I) atoms are linked by H(2)EIDC ligands, generating an infinite double chain along the a axis. These chains are further connected via O-H⋯O and N-H⋯O hydrogen bonds into a three-dimensional supra-molecular network.