A procedure for purification of single walled carbon nanotubes(SWNTs) grown by the chemical vapour deposition(CVD) of carbon monooxide has been developed. Based on the result from TGA/DTA of as prepared sample, the oxidation temperature was determined. The process included sonication, oxidation and acid washing steps. The purity and yield after purification were determined and estimated by TEM. Moreover, for the first time, a loop structure for CVD SWNTs has been observed. A process for purification of single walled carbon nanotubes (SWNTs) grown by the chemical vapor deposition (CVD) of carbon monooxide has been developed. Based on the result from TGA / DTA of as prepared sample, the oxidation temperature was determined. The process included The purity and yield after purification were determined and estimated by TEM. Again, for the first time, a loop structure for CVD SWNTs has been observed.