Poly[μ(2)-aqua-diaqua-(μ(8)-3-nitro-benzene-1,2-dicarboxylato)(μ(6)-3-nitro-benzene-1,2-dicarboxylato)tetra-sodium].

In the title layered coordination polymer, [Na(4)(C(8)H(3)NO(6))(2)(H(2)O)(3)](n), the doubly deprotonated 3-nitro-benzene-1,2-dicarboxyl-ate ligands exhibit μ(8)- and μ(6)-coordination modes to the sodium ions, generating sheets lying parallel to (001). The coordination environments of the sodium ions are distorted octa-hedral, distorted trigonal-bipyramidal and moncapped trigonal-prismatic. One of the nitro groups is disordered over two sets of sites with site-occupancy factors 0.580†(8):0.419†(2). A network of O-H⋯O and O-H⋯N hydrogen bonds helps to establish the packing.