The kinetics of MIE is theoretically analyzed to reveal the occurrence of macroscopic electric fields. An experimental technique to detect these fields is proposed. Self-oscillations in MLE systems are obtained. Relations between the amount of a microcomponent introduced into a MIE system and the reciprocal electric signal are determined. Numerous examples presented attest that the process of transient multispecies ion exchange generates a macroscopic electric field. This new phenomenon could be applied to ion analysis.