Ion exchange is widely used in hydrometallurgy, especially in the extraction of rare earth or dispersed elements from solutions. The field of application of ionites in non-ferrous metallurgy can be significantly expanded, firstly, if sufficiently cheap and high-capacity domestic ionites are available, and secondly, if the mechanism of the ion exchange process is known, which makes it possible to obtain, analyze and use appropriate kinetic equations. For a number of cations (copper, zinc, etc.), the domestic KU-2 cationite can be confidently attributed to the number of ionites meeting the first requirement. Not having selectivity with respect to ions of a certain grade in the combined presence of several ions, KU-2 cationite turns out to be quite capacious with respect to each of the cations individually.