Blends of isotactic polypropylene (IPP)/epoxy-modified lignin (LER)/glycidyl methacrylate grafted polypropylene (PP-g-GMA) have been subjected to both argon plasma exposure and electron beam bombardment, for different treatment conditions. The changes of their surface properties with respect to the untreated samples have been followed by means of contact angle measurements, ultraviolet-visible (UV-Vis) ellipsometry, X-ray photoelectron spectroscopy (XPS), and optical microscopy in polarized light. It was obvious that both treatment types led to the incorporation of polar groups on the exposed polymer films, groups responsible for all the observed modifications in their properties. The effects induced by the electron beam are higher when compared with those attributed to plasma exposure. Aging of the plasma exposed/electron beam bombarded polymer blends has been followed, evidencing different behaviors depending on LER content in IPP matrix. (C) 2003 Elsevier Science B.V. All rights reserved.