The H+ -ligand and M2+ -ligand equilibria (M2+=Ni2+ or Cu2+) of isophthalic acid dihydrazide were investigated potentiometrically using meticulous data acquisition and chemometric analytical techniques. Isophthalic acid dihydrazide possesses hydrazide groups on both sides of a benzene ring and is therefore capable of forming homo-and hetero-bimetallic species. The best-fit chemical models obtained through the Miniquad-75 program showed the existence of several mononuclear and binuclear complexes in different protonated, unprotonated, and deprotonated forms. The diagrammatic concentration distributions of the complexes against the pH of the solution were produced