Abstract: The microstructure and electrochemical properties of hybrids, combining singlewalled carbon nanotubes (SWCNTs) and DNA, were investigated. TEM images of the SWCNTDNA hybrids show that most bundled SWCNTs in the starting materials are isolated into individual ones during the sonicationpromoted selfassembly. AFM observation further indicates that the sidewalls of SWCNTs are helically wrapped by DNA, which results in stable SWCNTDNA complexes. The catalyst particles are totally removed during this selfassembly process, thus the SWCNTs are also purified. The electrochemical properties of the SWCNTs are substantially improved due to the hybridization of DNA and the specific capacitance of the SWCNTDNA hybrids is increased by of 117.9% compared to the parent SWCNTs.