Guest-host interactions in the Type I mixed clathrate hydrate with ethylene oxide and carbon monoxide guest molecules at temperature below 110 K are studied. By means of both molecular dynamics simulations and FTIR spectroscopy we investigate the hindering of rotational motion of guests molecules, the origin of this hindering, and the spectroscopically measurable consequences. Steric effects are responsible for restriction of rotational displacements of carbon monoxide. For ethylene oxide the rotational hindering is caused predominantly by van der Waals interactions between oxygen atom of guest and hydrogen atoms of water molecules. Creation of host-guest hydrogen bonds was not observed. (C) 2010 Elsevier B. V. All rights reserved.