XSW at total reflection condition providing element specific structural information about positions of ion species relative to the reflecting surface can be effectively applied to study organic macromolecules and lipid-protein systems of nanometer-range linear dimensions on solid or liquid surfaces. When applied to biomembranes, this technique can be used for “in vitro” study of their barrier, transport and protective functions. The objects of our investigation are: lipid-protein structures on a solid substrate as cell membrane models; different metal-rich organic monolayers alone on a water surface; self-assembling structure of lipids and protein on a water subphase.