
In this research work the proton-ligand dissociation constant of [2-oxo-2H-chromene-3-carbo hydrazide] and metal-ligand stability constants of its complexes with metal ions (Ni+2 and Cu+2) have been determined potentiometrically at 298, 308 and 318 K. The stability constants of the formed complexes increased in the order: Ni+2 > Cu+2. The effect of temperature was studied and the thermodynamic parameters (ΔH, ΔS and ΔG) were derived and discussed. The dissociation process was endothermic and spontaneous. The formation of the metal complexes has been found to be spontaneous and endothermic.