N-Acryloyl-4-aminosalicylic acid (AAS) was synthesized and characterized using different spectroscopic techniques. The geometrical structures of the ligand are carried out by HF method with 3-21G basis set. The proton-ligand dissociation constants of AAS and its metal stability constants with (Mn2+, Co2+, Ni2+ and Cu2+) have been determined potentiometrically in monomeric and polymeric forms using 2,2’-azobisisobutyronitrile as initiator. The potentiometric studies were carried out in 0.1 M (KCl) and 20% (by volume) ethanol-water mixture. The effect of temperature was studied at (298, 308 and 318 K) and the corresponding thermodynamic parameters (ΔG, ΔH and ΔS) were derived and discussed. The dissociation process is non-spontaneous, endothermic and entropically unfavorable. The formation of the metal complexes has been found to be spontaneous, endothermic and entropically favorable.