We have developed purification and cutting process of single-walled carbon nanotubes (SWNTs) by integrating (1) an acid reflux treatment to eliminate metal particles, (2) an ultrasonication in the H2SO4/HNO3 and H2SO4/H2O2 to cut and polish the SWNTs, respectively, and (3) an ammonia gas treatment to remove residual carbon impurities and to repair the sidewalls of SWNTs. The final products with a higher purity than 98% are well dispersed in aqueous solution using Pluronic P123 dispersant, which has been rarely used for the SWNTs dispersion. The dispersed SNWTs solution can exist stably for over two months. (c) 2006 Elsevier B.V. All rights reserved.