An electrochemically controlled method to drive ion exchange within zeolites is applied to the incorporation of U, into NaY. The technique uses the polarised liquid/liquid interface to transfer sodium ions selectively - and controllably - from the exchange medium, into an adjacent organic phase. The electrochemical removal of the unwanted ions from the exchange medium drives equilibrium toward greater exchange of the desired ion. Analytical data in support of the ion-exchange process is presented and an approximate calculation of the extent of ion exchange, as a function of charge passed, is described. This method has the potential to be very effective for the exchange of ions with low affinity for the parent zeolites, and to reach 100% exchange. (c) 2007 Elsevier Ltd. All rights reserved.