The article discusses the ability of multilayer composite nano-structured coatings based on the Cr-CrN-(Ti,Cr,Al,Si)N system to resist wear factors activated with increasing temperature, such as diffusion and oxidation processes, as well as spinodal decomposition of the coating material. Investigators were carried out in turning C45 steel at the following cutting conditions: f = 0.2 mm/rev, ap = 1.0 mm, vc = 300 m/min. SEM and TEM techniques were used to investigate changes in nano-structures of coatings, as well as diffusion and oxidation processes. Of particular interest was the study of a layer of nanometric thickness on the rake surface of the tool, between the adhered material being machined and the surface nanolayers of the coating. The content of oxygen, iron, and metals the coating was investigated. A lot significant difference was revealed in the content of elements in the layer investigated, depending on the location of the area studied around a crater on the rake face of the tool.