In this study, the adhesion properties of adhesives and paints on wood-plastic composites (WPCs) after plasma treatment at atmospheric pressure and ambient air were investigated. Surface energy determination by means of contact angle measurements according to the Owens-Wendt approach and atomic force microscopy to detect changes in surface topography were carried out. An increase in the polar component of surface energy and an increase in surface roughness after plasma treatment were detected, indicating enhanced bond strength. To confirm these results, bond strength tests were conducted. By tensile bond strength tests, increased adhesion of waterborne, solventborne and oil-based paints on plasma treated surfaces was found. Furthermore, by shear bond strength tests, an increase in bond strength of plasma treated WPCs bonded with poly(vinyl acetate) and polyurethane adhesives was ascertained. (C) Koninklijke Brill NV, Leiden, 2008