Grounds are given for the use of isotachophoresis for the crystallization of ionogenic substances from electrolyte solutions. Regulating function is the basis of this new isotachophoresis trend. A device for isotachophoretic crystallization in capillaries, based on a capillary isotachophoresis instrument is described. The process of sodium chloride crystallization from aqueous solution is described in detail. The applicability of the general rules formulated is confirmed by crystallization of potassium and sodium chlorides, cesium nitrate and potassium perchlorate in cationic isotachophoresis, and potassium bichromate in anionic isotachophoresis.