A multifunctional catalyst for fuel cell applications, Pt/RuO2–SiO x /C, has been prepared by supporting platinum nanoparticles on surface-modified carbon black, fabricated by in situ hydrolysis of ruthenium and silicon precursors on pre-treated carbon black. The catalyst is extensively characterized by X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy. The catalyst shows high activity toward methanol oxidation and oxygen reduction at room temperature. Notably, the addition of ruthenium oxide significantly improves the performance of MEAs under non-humidified conditions. The self-humidification performance of MEAs prepared with Pt/RuO2–SiO x /C (using optimized 3wt.% RuO2) as the anode catalyst is enhanced by over 20% compared to MEAs prepared with Pt/SiO x /C as the anode catalyst. It is suggested that the promotion of RuO2 may result from the high dispersion of platinum caused by adding ruthenium oxide, and the synergistic effect of ruthenium oxide.