The adsorption of H@sub 2@O on Ru(001) and the coadsorption system H@sub 2@O+CD@sub 3@Cl/Ru(001) were studied using Temperature Programmed Desorption (TPD) and work function change (@DELTA@@PHI@) measurements. We developed a kinetic model that fits the measured @DELTA@@PHI@ upon water adsorption at 80K. The model indicates that at very low coverages water monomers dominate, while as coverage increases di- tri- and tetramers are formed. Water tetramers were observed recently by IR measurements to be the dominant species in similar adsorption conditions. The effective @DELTA@@PHI@ contribution of these species suggests an adsorbed cyclic tetramer, with inclined water dipoles. Molecular Dynamics (MD) simulations using the TIP4P potential energy surface for the water-water interaction, were performed as a means for gaining deeper insight into the experimental results. The effective dipoles of the small clusters obtained from the MD simulations were in good agreement with the dipoles predicted by the kinetic model. Adsorbed CD@sub 3@Cl molecules were found to be compressed and then caged under H@sub 2@O layers, as indicated by complex @DELTA@@PHI@ curves monitored upon adsorption. These are explained by the following sequence (a) H@sub 2@O molecules initially compress CD@sub 3@Cl into separate islands. Desorption from this stage suggests that the structure of methyl chloride resembles that of multilayer CD@sub 3@Cl, namely chlorine down in the first layer, while in the second layer it flips up. (b) Hydrophobic displacement of CD@sub 3@Cl from surface sites to become trapped within the water layer. Further increase of the water coverage produces a tight cage of the CD@sub 3@Cl molecules inside the ice structure, as indicated by a sharp, explosive desorption at 165 K.