2-Acrylamidosulphamethoxazole (ASM) was synthesized and characterized by elemental analyses, IR and H-1 NMR spectra. Proton-monomeric ligand dissociation and metal-monomeric ligand stability constants of ASM with some metal ions were determined potentiometrically in 0.1 M KCl and 40 % (vh) ethanol-water mixture. In the presence of 2,2'-azobisisobutyronitrile as initiator, the dissociation and stability constants of ASM were determined in polymeric form (PASM). The influence of temperature on the dissociation of ASM and the stability constants of their complexes in monomeric and polymeric forms were precisely studied. The pK(2)(H) value of PASM was found to be higher than ASM, this means that the vinyl group in the monomeric form decreases the electron density and hence reduces the N-H bond strength. The stability constants of the metal complexes in polymeric form are higher than those of the monomeric form. This reveals that the ligand in a polymeric form is considered as a better complexing agent.