In recent years nano- and microparticles composed of polymeric or lipid material have been proposed as drug carriers. Their use allows the modification of the biopharmaceutic properties of the drug without changing its molecular structure. In the past few years, using LS, CRYO-TEM and SANS, we have started a systematic structural study of nanocapsules obtained by self-assembling of phospholipids (soybean lecithin) in aqueous medium containing a fixed amount of chitosan, a positively charged polysaccharide, and pharmaceutical excipients that increase incapsulation efficiency of water insoluble drugs. We propose now to extend this study by QENS experiments to investigate the degree of association of hydration water to the different structures (single-layer coated vesicles and multilamellar vesicles) observed.