A purification procedure for single-walled nanotubes is presented in this report. A novel purification method that incorporates the hydrothermal treatment along with other treatments such as extraction of fullerenes and oxidation and dissolution of metal particles is used in this study. The effects of each treatment in the purification process is also discussed by characterizing the intermediate products using X-ray diffraction, Raman spectroscopy, scanning electron microscopy, and transmission electron microscopy.