[en] The method of ionfocussing was systematically investigated on thin layers of silica gel with toluene as a cooling medium. Quantitative relations between the amount of ions, the area of the focus, the concentration of electrolytes and the concentraton of ions in the focus were found. The conditions for separations were optimized and separations into five groups of ions could be achieved within some minutes. A combination between zone electrophoresis and ion-focusing yields even better separations. From the experimental results an explanation of the focusing effect can be given. Further a method for evaluation of data from autoradiographies was developed. (author)