A simple model based on a stage concept that can be used to predict the effects of operating variables on the separation of isotopes by chemical exchange is described. The particular application studied is chemical exchange of uranium isotopes in an ion exchange column that has NT total theoretical stages. Other important operating parameters are the number of stages in the exchange band Ns and the chemical exchange equilibrium constant ∈. A model of the process is developed and simulated by a computer program. The results are correlated to give simple expressions based on the assumption that one-half of the band that emerges from the column is taken as enriched feed with a concentration y. For small values of ∈, the optimum value of Ns is given by 1.313 and y = x0(1 + 0.551∈), where x0 is the feed concentration.