The formation constant of Tm (III)-systems with different sulphonanilide ligand namely 3-carboxy-4-hydroxy-4’-nitro benzene sulphonanilide, 3-carbmethoxy-4-hydroxy-4’-nitro benzene sulphonanilide and 3-carbethoxy-4-hydroxy-4’-nitro benzene sulphonanilide in DMF media have been determined with the help of spectrophotometeric method. Results shows that the stability of lanthanide complexes is found similar to [Ag (NH3)2] + type of complex.