Amino acids and peptides are among the most common biomolecules and they are considered as effective metal binding sites under physiological conditions. Cadmium belongs to a category of heavy metal ions (cadmium, mercury, lead) that have increasingly attracted research attention over the years, due to their toxic manifestations in the environment and various organisms, including plants and humans. The scope of this research is to probe and synthetically study the aqueous Cd(II)-glycylglycine speciation relevant to Cd(II) toxicity.