Nitrogen-containing microporous carbon nanotubes were prepared via the carbonization of polyaniline/silica nanotube composites in order to obtain a new type of carbon electrode material. As a carbon precursor, polyaniline was coated onto a silica nanotube and subsequent carbonization was performed at 850 degrees C. After carbonization and silica etching, the nitrogen-doped carbon nanotubes (N-CNTs) show a 10 hollow structure with a high specific surface area; then, the N-CNTs are chemically activated using a KOH solution. It was found that the specific surface area of the activated N-CNTs (AC-N-CNTs) significantly increased to 1958 m(2)/g with chemical activation compared with N-CNTs (217 m(2)/g). In addition, the specific capacitance (254.6 F/g) of the AC-N-CNTs was higher than that of the N-CNTs (218.6 F/g). This superior performance is attributed to the synergistic effect between the high specific surface area and nitrogen group of the AC-N-CNTs, indicating the combination effect of both the electric double layer capacitance and pseudocapacitive reaction. (C) 2012 Elsevier Ltd. All rights reserved.