Polytetrafluoroethylene (PTFE) was irradiated by low energy titanium ion in a metal vapor vacuum arc (MEVVA) implanter. The samples were irradiated with 80 keV Ti ion with fluences from 5 x 10(15) to 5 x 10(17) Ti/cm(2), respectively. Transportation of Ion in Matters (TRIM) code was employed to simulate Ti ion irradiation. The as-irradiated samples were investigated by ESCA, SEM and wettability. As increasing ion fluence, various chemical bonds and irradiation-damaged surfaces were observed. The water droplet contact angel of PTFE samples increased gradually with ion fluence. All the as-irradiated PTFE samples were aged in air for I year. After aging the surface-restructuring behavior was observed on the surfaces of the samples irradiated with ion fluence equal to or less than 5 x 10(16) Ti/cm(2), which resulted in decrease of the droplet contact angle of these samples. The surface roughness change of the aged samples, which were measured by atomic force microscopy (AFM), was consistent with the droplet contact angle change. The experimental results revealed that Ti ion fluence closely affected the surface chemical bond, morphology and wettability, as well as the aging stability of the as-irradiated PTFE samples. (C) 2002 Elsevier Science B.V. All rights reserved.