By employing temperature-programmed desorption and time-of-flight secondary ion mass spectroscopy, the adsorption of water on the hydrophilic and hydrophobic surfaces of a lipid ( DPPC) film has been investigated. It could be shown that it is possible to prepare lipid films ex situ with a preferential orientation of the lipid molecules on a solid support and to retain their specific properties under ultrahigh vacuum conditions. The water adsorption and desorption kinetics on the hydrophilic and hydrophobic surfaces provided by a lipid film are discussed in terms of their structural and chemical properties.