We present a novel methodology for the study of proteinaceous films based on the friction force spectroscopy operation mode of the atomic force microscope. It provides information both on the strength at the nanoscale level and on the lateral diffusion properties of these systems. The usefulness of the data generated by this methodology are shown through its application to the study of different types of monolayers of model proteins, as well as to the study of the more complex and heterogeneous salivary films.