The aim of this work was to study the durability of a polypropylene film plasma-treated with an 80 : 20 methane-oxygen gas mixture. Three different storage conditions were used to evaluate the influence of the relative humidity and temperature on the aging process. The surface funcitonalization of the polypropylene film was analyzed with X-ray photoelectron spectroscopy and attenuated total reflectance/Fourier transform infrared spectroscopy analysis, and the variations of the surface energy and its polar and dispersive components were also investigated. The effects of this plasma treatment were similar to those of a plasma polymerization process, the ablation and polymerization mechanisms taking place simultaneously at the treated surface, but in this case, we obtained hydrophilic properties. The obtained results indicated an improvement of wettability and high durability of the plasma-trated polypropylene film. (c) 2008 Wiley Periodicals, Inc.