Fast charging-discharging performances of well-dispersed RuO2 nanoparticles (NPs) on N-doped carbon nanotubes (CNTs) have been demonstrated. As regards the structural properties, the N 1s x-ray photoelectron spectroscopy spectrum shows two characteristic bonding peaks of N within CNTs. Cross-sectional scanning electron microscope images show that N-doped CNTs provide good support for uniform distribution of RuO2 NPs. As regards the capacitive behavior, N-doped CNTs covered with well-dispersed RuO2 NPs lead to a high charging-discharging property performed at the scan rate of 2000 mV s-1. The role of N doping is to create preferential sites of CNTs for capturing RuO2 NPs. Such a fast sweep capability established by the N-incorporation method is very useful in supercapacitor applications.