By computer calculation three cases of multiplication of isotope effect, corresponding to peculiar parameters of isotopic exchange reaction between U(IV)resinand U(VI)solutionwere considered: 1) inverse break-through; 2) direct break-through and 3) band displacement processes. In the first case the interesting part is located at the end of the elution curve, where a sharp decrease of235U content occurs. In the second case the frontal part is enriched in235U. Although the band displacement is a combination of both direct and inverse break-through processes, only in this case it is possible to obtain an equilibrium isotopic composition of the band, corresponding to the maximal isotopic modification of the whole uranium adsorbed in the band. The stationary equilibrium isotopic composition depends on the displacement lenght of the band, which is increased when the band is longer; it depends also on the physico-chemical factors and especially on the equilibrium constant (separation factor) of the isotopic exchange reaction.