The asymmetric unit of the title compound, [Rb(C(7)H(3)N(2)O(6))(C(7)H(4)N(2)O(6))](n), comprises an Rb(+) cation, a 3,5-dinitro-benzoate anion and a 3,5-dinitro-benzoic acid ligand. The Rb(+) cation is nine-coordinated by O atoms from four 3,5-dinitro-benzoate anions and three neutral 3,5-dinitro-benzoic acid ligands. The metal atom is firstly linked by four bridging carboxyl groups, forming a binuclear motif, which is further linked by the nitro groups into a two-dimensional framework along the [110] direction. A short O-H⋯O hydrogen bond between two adjacent carboxy/carboxylate groups occurs.