Cotton fabrics were treated by radio-frequency plasma with tetrafluoromethane (CF4) and hexafluoropropene (C3F6) gases under different exposure times, pressures, and power levels. The hydrophobicity and water repellency were analyzed with measurements of the cosine of the contact angle (cos theta) and wet-out time. The hydrophobicity was enhanced with treatments of both gases. Xray photoelectron spectroscopy (XPS) revealed increases in the surface fluorine content of 1-2% for CF4 plasma and of 2.3-7.8% for C3H6 plasma. The relative chemical composition of the C-1s spectra after CF4 and C3F6 plasma treatments showed increases in the relative amounts of -C-O-C-and fluorocarbon groups (-CF, -CF2, and -CF3), whereas peak areas for -COH and -COOH decreased. The hydrophobicity was enhanced by the increase in the fluorine content and fluorocarbon groups. CF4 plasma treatment resulted in higher hydrophobicity than CF4 plasma treatment according to not only cos theta and wet-out measurements but also XPS analysis. (C) 2003 Wiley Periodicals, Inc.