The reorientational relaxation of benzene, toluene, and p-xylene, which are clathrated in the delta form of crystalline syndiotactic polystyrene, was investigated using a molecular dynamics simulation. The structures of the cavity, the host-guest interactions, and the resultant effects on the reorientational. dynamics of the guests-were investigated in detail. The relaxation time of the in-plane phenyl ring reorientation of benzene about its C-6 symmetry axis obeyed the Arrhenius law in the wide temperature range. It was found that the host-guest interactions in the clathrate compounds are significantly affected by the molecular structure of the guests. (C) 2003 Elsevier Science B.V. All rights reserved.