The sorption kinetics of 1,2-dichloroethane (DCE) (pure or dissolved in water at different concentrations) in amorphous and semicrystalline syndiotactic polystyrene films are studied by Fourier transform infrared spectroscopy. Experiments at low DCE concentrations show that the DCE sorption in empty-clathrate samples is much faster and leads to much higher sorption equilibrium values than that in the amorphous or other semicrystalline samples. The results of the sorption experiments into emptied clathrate polymer samples can be interpreted by assuming that DCE, for low concentrations in aqueous solutions, is mainly absorbed by the clathrate phase and that, as guest molecule in the polymeric clathrate, it is substantially only in the trans conformation. In the assumption that the guest DCE molecules in the clathrate are present only in the trans conformation, the kinetics of clathration in the emptied clathrate phase and of sorption in the amorphous phase are separated.