This thesis focuses on the hydrophobicity improvement of fabrics which included polyethylene terepthalate, Thai silk, mixed Thai silk and cotton using radio frequency inductively coupled SF₆ plasma. All treated fabrics show significant improvement in hydrophobicity. Compared with untreated fabrics, contact angle of treated fabrics increases about three times and absorption time increases from 0-30 minutes to the maximum observation time limit of 210 minutes. The change in surface morphology was observed by scanning electron microscopy and atomic force microscopy. The average roughness increased from 3-28 nm to 23-45 nm, depending on type of fabrics. The changes in chemical compositions on fabric were invertigated by X-ray photoelectron spectroscopy (XPS). The XPS results show the participation of fluorine-containing groups (CF, CF₂, CF₃) in fabric surface as well as the increase of total fluorine content after SF plasma treatment. The fluorine content were related to the absorption time. We found that the main reason for the improvement of hydrophobicity properties of fabrics should due to the incorporation of fluorine atoms rather than the increase of surface roughness. In this study, the increase of surface roughness was found to be in the order of nanometer range which is very small compared to the size of water droplet used in the experiment. In our RF-ICP system, the optimum operating plasma condition is obtained at pressure of 0.5 Torr and RF power of 50 watts.