It is the aim of the proposal is to perform neutron reflectivity (NR) studies combined with contrast variation to determine the structure of phospholipid monolayers on a non-polar solvent (namely a diol either 1,2 propanediol (propylene glycol), 1,3 propanediol, 1,2 butanediol or 1,4 butanediol or a triol 1,2,3 propanediol (glycerol)) at the air-solvent interface. Of particular interest is the effect of the structure of the solvent on the formation of monolayers of the phospholipid, 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC). The information gained from these studies (e.g. are per molecule and lipid thickness) will aid the understanding of the structures this lipid, POPC, forms in the non-aqueous polar solvents and will inform the future development of these interesting and potentially important delivery systems.