The surfaces of a homologous series of fluoropolymers were characterized in sit using X-ray photoelectron spectroscopy before and after a 15-min exposure to the flux produced by a unique hyperthermal atomic oxygen (AO) source, which produces a flux of about of 10(15) atoms cm(-2) s(-1). The linear polymers investigated in this study include high-density polyethylene (HDPE), poly(vinyl fluoride) (PVF), poly(vinylidene fluoride) (PVdF), and poly(tetrafluoroethylene) (PTFE). They possess a similar base structure with increasing fluorine-to-carbon ratios of 0, 1 : 2, 1 : 1, and 2 : 1, respectively. No interaction of the AO with the nonfluorine-containing linear polymer HDPE was detected over this short exposure. However, a correlation exists between the chemical composition of the fluorinated polymers and the induced chemical and structural alterations occurring in the near-surface region as a result of exposure to AO. The data indicate that AO initially attacks the fluorine portion of the polymers, resulting in a substantial decrease in the near-surface fluorine concentration. The near-surface fluorine-to-carbon ratios of PVF, PVdF, and PTFE decreased during the 15-min AO exposure by 68, 39, and 18.5%, respectively. (C) 2004 Wiley Periodicals, Inc.