Potassium titanate ion exchanger was synthesized to use for removing strontium and caesium ions, which are the heat generation radionuclides in HLLW(high level liquid waste). Adsorption equilibria for Sr and Cs ions were evaluated with the synthetic potassium titanate(K2Ti4O9) ion exchanger. The potassium titanate ion exchanger showed selective adsorption for Sr ion over Cs ion. The distribution coefficients for Sr and Cs ions at pH 2 were 3,300 mL/g and 200 mL/g, respectively. Standard isotherm equations such as Langmuir, Freundlich and Dubinin-Polanyi equations were used to model the experimental data. For the binary data modeling, even though all models fit the data, Freundlich model and Dubinin-Polanyi model fit the experimental data more correctly. For multicomponent system, however, the experimental data could not be predicted from binary data using standard isotherms. While, a modified version of Dubinin-Polanyi equation, which is a semi-empirical equation, fit the experimental data accurately.