The new complex of Co (II) with 2-nitroterephtalic acid was synthesized and its molecular and crystallic structures were studied. It was found the structure consists of polymeric chains of the dianion of nitroterephtalic acid formed by hydrogen bonds, between which the cobalt hexahydrate cations are located. Including into complex composition pyridine molecule was not coordinate with cobalt (II) ion, but formed an adduct with polyanion of 2-nitroterephthalate through hydrogen bonds