The asymmetric unit of the title compound, [Na(2)(C(8)H(8)O(8))](n), contains one Na(+) ion and half of a 2,3-bis(carboxymethyl)butanedioate (H(2)BTC(2-)) dianion, which lies on a center of symmetry. The dianion exhibits a μ(10)-bridging mode. Each Na atom lies in a NaO(6) octa-hedron defined by six O atoms from five dianions. Adjacent NaO(6) octa-hedra share a common O-O edge, generating a biocta-hedron; adjacent biocta-hedra are O-O edge-connected to one another, building up a chain along [001]. The chains are connected by adjacent H(2)BTC(2-) anions into a three-dimensional framework. The structure is further stabilized by O-H⋯O hydrogen bonds.