Dynamic response performance of proton exchange membrane (PEM) fuel cells affects its durability and reliability significantly. In this study,electrodeposited RuO2. xH2O-Pt/C was prepared to promote the PEM fuel cell dynamic response performance.The prepared RuO2. xH2O-Pt/C was characterized by scanning electron microscopy (SEM) equipped with energy disperse spectroscopy (EDS), which shows that RuO2· xH2O was electrodeposited on the surface of Pt/C. Performance of single cells with and without RuO2 · xH2O-Pt/C at the cathode under a certain operating condition was studied using cyclic voltammetry, electrochemical impedance spectra (ELS) and polarization curve techniques. When the fuel cell modified with RuO2·xH2O-Pt/C was operated at lower pressure, a faster and more stable dynamic response could be found. Modifying with RuO2 · xH2O-Pt/C composite material not only slightly increases the single cell performance but also dramatically improves the dynamic response performance, revealing that RuO2·xH2O-Pt/C can buffer the voltage undershoot whenever the current increases instantly.