Two polymeric ferro-complexes were first synthesized from FeSO 4 .7H 2 O and poly(Schiff base)s. The poly(Schiff base)s were prepared by polycondensation of 5,5'-dimethyl-2,2'-diamino-4,4'-bithiazole (MDABT) with oxalic aldehyde and isophthalaldehyde, respectively. The structures of polymers and complexes were characterized by IR and 1 H NMR spectra. The Fe contents of complexes were measured by X-ray spectrometer. The magnetic behavior of the complexes was examined as a function of magnetic field strength at 4K and as a function of temperature (4-300K). The results show that PMTOA-Fe 2 + is a soft ferromagnet while PMTIA-Fe 2 + exhibits features of an antiferromagnet.