An unusual series of amphiphilic molecules that form surface films on water have been investigated using a combination of Langmuir¿Blodget, ellispometric, and non-linear laser spectroscopic (SHG) techniques. These molecules are likely to make a significant contribution to the nature of the sea surface micro-layer and thus influence air-sea exchange and wave behaviour. An unusually rigid compressed film has been observed at the air-water interface in a number of the samples collected from marine environments and the pure amino acid surfactants are ideal model compounds with which to understand the behaviour of the natural films. We will determine the structure of films of these pure surfactants formed at the air water interface as a function of lateral surface pressure using neutron reflection.