Abstract: The possibility of producing oleophobic monolayers containing more than one component (mixed monolayers) is investigated. It is shown that homogeneous mixed monolayers containing components which are very different in their properties and molecular shape may be easily formed on various solid polar substrates by adsorption from organic solutions. Irreversible adsorption may also be achieved through covalent bonding of active silane molecules to the surface of the substrate. Details regarding the structure and the formation of mixed monolayers are revealed by means of spectroscopic methods using surfaceactive dyes as monolayer components. By studying the time dependence of formation it is shown that interactions involving both the molecules in the adsorbed state and those in solution lead to large fluctuations in the composition of mixed monolayers containing only reversibly adsorbed components, while irreversible adsorption tends to stabilize certain final compositions which are monotonically approached. It is concluded that adsorption on well-defined solid surfaces might be developed into a suitable method for producing monomolecular films with a controllable molecular organization.