The objective of this research was to obtain an optimal combination of superhydrophobic coating treatment on the surface of carbon nanofibers (CNFs) by means of design of experiments (DOE) and analysis of variance (ANOVA). Four factors, including fluoride ratio, spinning speed, coating time, and thermal treatment temperature, were considered in this research. For robustness concern, we applied DOE and ANOVA to our experiments with a 95% confidence interval. Analyzed results reflect that the fluoride ratio was the most significant among all factors. We also verified the impact of surface roughness on contact angle. The average contact angles on CNFs increased from 125 degrees +/- 2.5 degrees to 162 degrees +/- 2.5 degrees after treatment. This research is directed toward the applications of hydrophobic coating, such as biological detectors, hydrophobic products with self-cleaning function, material with bacteria-proof function, etc. (c) 2006 American Vacuum Society.