Chemical-physical properties of ultra-high-molecular weight polyethylene (UHMWPE) treated by direct fluorination, direct fluorination accompanied with UV irradiation, by XeF(2) and by TbF(4), were tested by FTIR spectroscopy, visible spectroscopy, 19F and 13C NMR, scanning electron microscopy, XRD, and EPR. Surface energy measurements were carried out. The direct fluorination of UHMWPE is a diffusion-controlled process, but treatment with XeF(2) is a kinetically controlled one. Direct fluorination and direct fluorination accompanied with UV irradiation results mainly in a formation of-CF(2)-groups. On the contrary, -CHF- groups are prevailing in UHMWPE treated with XeF(2) and TbF(4). Surface texture of UHMWPE treated with XeF(2) and with F(2) is quite different. Direct fluorination results in a higher polarity of the polymer surface when compared with treatment with XeF(2). For the case of direct fluorination, both long-lived peroxy and fluoroalkylradicals are formed. For the case of treatment with XeF(2), only fluoroalkylradicals were detected. (C) 2011 Wiley Periodicals, Inc. J PolymSci Part A: PolymChem 49: 3559-3573, 2011