The structure and energetics of water adsorption on the rutile TiO₂ (110) and SnO₂ (110) are investigated using the spin-polarized density functional theory formalism. The electron-ion interaction term is described by the projector augmented wave method and the generalized gradient approximation scheme has been adopted to calculate the total energy. The results reveal that in both surfaces, the H₂O molecules prefer the 5-fold metal site (Ti or Sn). However, there is a significant difference in the adsorption behavior in terms of chemical bonding. While for TiO₂ (110) surface, water molecules are adsorbed without losing its molecular identity, on the SnO₂(110) surface water molecules prefer dissociative adsorption.