A 3-D network polymer, Mn(NITpPy)(2)(tp)(H2O)(2), has been synthesized and structurally and magnetically characterized. In the, crystal structure, the 1-D chains are formed by [Mn(NITpPy)(2)](2+) units and terephthalate ligands, and they are linked together by hydrogen bonds to give rise to a 3-D network. Magnetic measurements show that weakly ferromagnetic coupling exists between the Mn(II) ion and nitronyl nitroxide radical and weakly antiferromagnetic interaction exists between Mn(II) ions through terephthalate.