The effect of fluorination on carbon blacks (CBs) was investigated by analyzing the CB surface functional groups. Also, fluorinated CB supported platinum-ruthenium electrocatalysts were studied. The surface characteristics of the fluorinated CB-supported catalysts were determined by Fourier transform infrared (FT-IR) spectroscopy and X-ray photoelectron spectroscopy (XPS), and their crystallinity was evaluated using X-ray diffraction (XRD). The electrochemical properties of the fluorinated CB-supported platinum and ruthenium (Pt/Ru CBs) catalysts were analyzed by cyclic voltammetry (CV). From the FT-IR results, the introduction of a fluorine atom onto CBs was confirmed by the existence of a carbon-fluorine (C-F) characteristic peak. The XPS result also showed that the fluorine content increased with increasing heat treatment temperature. The XRD analysis revealed that the catalysts are composed of mostly Pt and Ru. This result agreed with the fact that the electrochemical activity of the Pt/Ru CB catalysts was enhanced due to the small size and a high loading of catalysts by surface modification of the CBs.