A Fourier transform infrared spectroscopy investigation relative to clathrate forms of syndiotactic polystyrene (s-PS) with chlorinated organic compounds is presented. In particular, for 1,2-dichloroethane (DCE), 1,2-dichloropropane (DCP), and 1-chloropropane (CP), the absorption peaks which are modified as a result of clathrate formation have been identified and analyzed. The study has shown that in the polymeric clathrate phase, a nearly complete conformational selectivity occurs for DCE and DCP, while the conformational equilibrium of CP remains substantially unaltered. Both for DCE and DCP, the conformational selectivity is in favor of conformations leading to trans chlorine atoms and is associated with specific attractive interactions involving the chlorine atoms. The observation of shifts of C-Cl stretching bands indicates that attractive interactions are possibly established between chlorine atoms and aromatic rings, both in amorphous and in clathrate phase of s-PS.