A model for multispecies ion-exchange kinetics based on the Nernst-Pla
nck equation is suggested. It is analyzed in comparison with the ''loc
ally-determinate'' model described by Hwang and Helfferich [1]. The mo
del makes possible simple computation. The conditions for the occurren
ce of unusual kinetic curves with a maximum are clarified. The propose
d model is developed for different types of kinetic problems and verif
ied by the experimental investigation of a kinetics in ternary systems
.