A mathematical model has been developed for the extraction of oligomers from granular polymers with solvent. The model accounts for effective diffusion of the oligomer in the polymer pearls, axial dispersion of the pellets and liquid phase and distribution equilibrium at the interface. The results of numerical simulations of the model are consistent with experimental data. The influence of the physico-chemical parameters on the oligomer concentration in the pellets is shown in terms of a sensitivity analysis. The model can be used for analysis and design calculation of extraction of oligomers either in batch or continuous processes.