The properties of the surface layer of construction materials are very important for making adhesive bonds. The article presents the test results for surface free energy in PA6 polyamide subjected to surface layer modification using the ozonation process. To develop the surface geometrically, the samples were subjected to mechanical processing. The comparison of results demonstrated that ozonation is an efficient and eco-friendly method of modifying the surface layer. The article also presents the comparison results for measurements of selected surface roughness parameters.