Method for the removal of ions and ionizable substances from a polar liquid (10) comprising at least one process wherein said polar liquid (10) is split into a first stream (F1) and a second stream (F2), Said first stream (F1) passing through an electrochemically regenerable ion-exchange material (2) located where an electric field between two electrodes (4, 5) is applied, said first stream (F1) flowing from one electrode (4) to the other electrode (5) so that the ions to be removed are migrating in the direction reverse to the first stream flow through said ion-exchange material (2), Said second stream (F2) rinsing said one electrode (4), and said material is regenerated by the ions which are formed at the other electrode (5). Device in particular for the implementation of said method.