Poly(tetrafluoroethylene-co-hexafluoropropylene) (FEP) surfaces were exposed to vacuum UV (VUV) photo-oxidation downstream from Ar microwave plasma. The modified surfaces showed the following: (1) an improvement in wettability as observed by water contact angle measurements; (2) surface roughening; (3) defluorination of the surface; and (4) incorporation of oxygen as CF-O-CF2, CF2-O-CF2 and CF-O-CF3 moieties. With long treatment times, a cohesive failure of copper sputter-coated onto the modified surface occur-red within the modified FEP and not at the Cu-FEP interface.