In the polymeric title compound, [Co(2)(C(3)H(7)NO)(3)(C(8)H(3)NO(6))(2)]·C(3)H(7)NO, one 5-nitro-isophthalate dianion has its two carboxyl-ate groups chelating to one Co(II) atom while simultaneously coordinating to another metal atom in a μ(4)-bridging mode. The other 5-nitro-isophthalte dianion has one carboxyl-ate group chelating to a metal atom whereas the other bridges two metal atoms in a μ(3)-bridging mode. Both metal atoms show an octa-hedral coordination. The polymer adopts a layer motif, with the lattice dimethyl-formamide mol-ecules occupying the space between adjacent layers.