In this Work, the binary ion exchange of Zn(2+)-Na(+) ions has beer Studied by a column technique using a NaY zeolite as the cation exchanger. The experimental data (breakthrough curves) for the system were obtained at total concentrations of (1, 2, and 3) meq.L(-1) The mass action law was used to represent the ion exchange equilibrium. To represent the ion exchange in the column, two models were used. In the first model the rate-controlling step of mass transfer was considered only in the solid phase. The-experimental results were represented by a Linear Driving Force (LDF) model. In the second model, resistance to mass transfer in series in the solid phase and the external liquid film was considered. both models described ion exchange in the fixed-bed column properly, However; in the initial part of the breakthrough curve, the dual resistance model fit better.