Thermally stable and porous RuO2 center dot xH(2)O with superior rate-retention capability is prepared by the H2O2-oxidative precipitation method modified with the cetyltrimethylammonium bromide (CTAB) template. The specific capacitance and rate-retention of RuO2 center dot xH(2)O are considerably enhanced by the CAB modification and annealing at 200 degrees C because of extremely localized crystallization and pore opening of slightly sintered RuO2 center dot xH(2)O nanoparticles trapped with CTAB. This unique structure, confirmed by the X-ray absorption spectroscopic (XAS), Raman spectroscopic, and transmission electron microscopic (TEM) analyses, favors the utilization of RuO2 center dot xH(2)O nanocrystals and increases the electrolyte accessibility in comparing with RuO2 center dot xH(2)O without CTAB modification. The preferential orientation growth along the {101} facet of RuO2 nanocrystals in some local regions is acquired by the CAB modification and annealing in air at temperatures >= 350 degrees C. Such preferential orientation growth of RuO2 crystallites is attributable to the oxidation of trapped surfactants during the thermal annealing process, which adsorb on the high surface energy planes of RuO2. (C) 2014 Elsevier B.V. All rights reserved.