Abstract <p>The interaction of copper(II) ions with natural lipids (soy lecithin, which has a different phospholipid composition) in an aqueous medium has been studied. It was found that lecithin forms sufficiently large liposomes with a diameter of about 900 nm in an aqueous medium, the size of which decreases in the presence of copper(II) ions regardless of their concentration, using thin-layer chromatography, dynamic light scattering, and mathematical processing of UV spectra using the Gauss method. It has been established that copper(II) ions both initiate the processes of lipid peroxidation and form complexes with the polar “heads” of phospholipids. It has been shown that these processes depend on the composition of lecithin lipids and their oxidation ability.</p>