Specific capacitances of the carbon nanotube (CNT) electrodes are significantly enhanced by using the nanoporous alumina templates with high pore density and uniform pore diameter. Well-ordered nanoporous alumina templates were fabricated by a two-step anodization method by applying a constant voltage of 25.0 V or 20.0 V in sulfuric acid solution. The cylindrical pore diameter and pore density of the templates prepared at the anodizing voltage of 25.0 V or 20.0 V were 53 +/- 1 nm and 3.1 X 10(10) cm(-2) or 38 +/- 2 nm and 3.8 x 10(10) cm(-2), respectively. The CNTs with uniform diameters of 44 +/- 2 nm in the 53 nm pores and of 32 +/- 5 mn in the 38 nm pores, respectively, were grown on the porous alumina template. For the electrochemical double layer capacitors (EDLCs), the aluminum metal below the porous alumina layer was used as a current collector for the CNT electrode without any binding material. The EDLC characteristics were analyzed by measuring the capacitances from cyclic voltammograms and the charge-discharge curves. A maximum value of 175F g(-1) was achieved for the specific capacitances of the CNT electrodes prepared on the alumina templates with high pore density. (c) 2006 Elsevier B.V. All rights reserved.