Zn and Cu interactions with three selected flavonoids (catechin, quercetin and rutin) have been electrochemically monitored. It has been shown that catechin takes 1 atom of metal per molecule; quercetin takes 2 atoms, and rutin is able to take up to 3 atoms. Not all ligands bind metals equally strong, and weakly bonded metals can be distinguished. Zn shows a sluggish kinetics and, at the same time, the highest conditional formation constants. The method could be applied to a real sample. Theoretical models are proposed for the most favourable compounds.