Fluorination plasma treatments at atmospheric pressure were used to modify the surface composition of EPDM elastomer. In this study, two different precursors (CF4 and SF6) and two carrier gases (He and Ar) were used for the surface modification of EPDM elastomer. The surface modifications were studied by means of X-ray photoelectron spectroscopy. We have observed a strong influence of the gas selection on the extent of the surface modification induced with these treatments. In general terms, the use of CF4 generates a higher concentration of fluorine in the elastomer surface. On the other hand, the use of He as carrier gas also increases the effectiveness of the modification process. The fluorine uptake varies between 2 and 13%, although the formation of fluorine-containing functional groups was detected when the amount of fluorine on the surface exceeded 7%. After all treatments, an important oxygen uptake was observed, with amounts three or four times higher than the untreated elastomer. (C) 2010 Elsevier B.V. All rights reserved.