Two novel fully conjugated polymers containing bithiazole rings (PDDBTz and PDABTz) were first synthesized by polycondensation of 2,7-dimethyl-2,4,6-octatriene- 1,8-dial with 2,2'-bis(diethylphosphinatyl methyl)-4,4'-bithizole or 2,2-diamino-4,4'-bithiazole (DABT). The structure of the polymers was determined by IR, H-1 NMR and elemental analysis. PDDBTz is soluble in trifluoroacetic acid and DMSO, whereas PDABTz is soluble in common solvent such as THF, DMSO, DMF. Bithiazole rings were introduced to provide bidentate N-donor sites for binding metal ions: Their lanthanide metal complexes were prepared. The magnetic behavior of these polymeric complexes was measured as a function of magnetic field strength (0-60 kOe) at 4 K and as a function of temperature (4-300 K) at magnetic field strength of 30 kOe. The results show that they all exhibit features of soft ferromagnet. (c) 2005 Elsevier Ltd. All rights reserved.