The performance of a material in a biological environment is mainly mediated by its surface properties and the combination of chemical, physical, biological, and mechanical properties required for a specific application. In this study, the surface of a thermoplastic polyurethane (TPU) material (Elastollan (R) 1180A50) was successfully modified by plasma treatment. Two different working gases were studied: argon and oxygen, which promoted the incorporation of oxygen-containing groups on the surface. The optimal plasma parameters were investigated by evaluating the wettability of the surfaces. Changes in the surface functional groups chemistry were studied using X-ray photoelectron spectroscopy (XPS). The obtained results showed that the plasma treatment process caused surface modifications that, in all cases, increased the polar nature of the surface. In terms of the desirable properties, it was found that the best operational conditions were: 100 W gas plasma, under a pressure of 60 Pa for 3 min. Argon seems to be more efficient then oxygen, because lower water contact angle results were obtained. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 2302-2308, 2011