Due to their high stability, wide analytical and industrial applications, metal i2n complexes of polyamino carboxylic acid ligands such as EDTA-4 (Ethylene diaminf tetra acetate), HEDTA-3 (Hydroxy ethylene diamin triacetate), DCTA-4(Cyclohexane diamin tetra icetate) and DTPA5- (Hydroxy ethylenediamine triacetate) have been the subject of much interest and investigation. On focus in this article are the various studies, carried out in order to understand the kinetic and aqueous solution behaviour of these complexes.