Abstract: In this work, the fifteen coordination compounds of rare earths with sulfa-methoxypyridazine were prepared in methanol medium. The compositions of the new coordination compounds were determined as LnA₃·nCH₃OH·mH₂O(Ln= different rare earth ions, A=ion of sulfamethoxypyridazine), and their IRabsorption spectra,¹HNMR spectra, TGcurves, X-ray powder diffraction, electric conductance and the solubilities in various solvents have been investigated, and their structures of coordination compounds were discussed.