ZnO nanostructure is a material that is central for many nanotechnology applications, such as chemical and biological sensors. A systematic molecular dynamics study for the behaviour of water droplet and electrolyte solutions interacting with ZnO was concluded. The contact angle of a water droplet on ZnO polar slabs and nanorods/-tubes array changes significantly as a function of the ZnO-water interaction energy and nanostructure geometry. The water contact angle served as a criterion to tune the intermolecular interactions. This book uses ZnO nanotubes to study the permeation of water for equilibrium and applied voltage cases in order to illustrate the influence of the surface topography and the intermolecular parameters and surface charges on permeation kinetics.