Thesis: The aim of this work was to develop a robust and generical model able to predict 137Cs mobility into the soil-solution-plant continuum. The first part of this work was dedicated to several soil-plant transfer experiments. Two plants (millet, mustard) with contrasted Cs adsorption capacity and three soils with different Cs retention capacities have been used. Results obtained with the experiments permitted to observe the influence of the different system compartments on Cs mobility. Moreover, those experiments permitted to acquire a contrasted experimental data set. The second part of this work was to confront the model with the experimental data generated in the lab. This confrontation showed that the model was able to represent with a good agreement the distribution of the Cs into the soil-solution-plant continuum. Moreover, the model permitted to understand the influence of other cations in the mobility Cs in the system. Dynamic modeling of the 137 Cs in the soil-solution-plant continuum. Evaluation of the model response to contrasted experimental data