The structure and thermodynamics of water adsorbed at the (110) surface of rutile (α-TiO^sub 2^) and cassiterite (α-SnO^sub 2^) were studied by means of molecular dynamics simulations with atomic interactions represented by a classical forcefield based on the SPC/E model of water. To investigate the effect of surface water dissociation on the adsorption of additional layers of water, two extreme cases of completely hydroxylated and nonhydroxylated surfaces were considered. Axial density distributions and adsorption Helmholtz free energies of water for different types of surfaces were compared and related to thermal gravimetric analysis data from literature. We found that the ...