Using perfluoropolyether as the solvent, cutting of pristine SWNT has been achieved by extensive ozonolysis with 80% carbon yield at room temperature. The intense disorder mode in the Raman spectra of ozonated SWNT indicates that extensive reaction with the sidewalls of SWNT occurs during ozonolysis. AFM provided a measure of the extent of the cutting effects. Monitoring of the evolved gases indicates CO2 was produced during the ozonolysis process with a dependence on both system pressure and temperature. During heating, FTIR analysis of gases released indicates carbon oxygen groups on the sidewalls of SWNT are released as CO2. Room temperature ozonolysis of fluorinated SWNT and phenol-sulfonated SWNT have also been studied in PFPE. For fluorinated SWNT, etching at the end caps has been demonstrated to be the dominating effect during this process. The improved suspension in 96% sulfuric acid after ozonolysis enables the cutting by ammonia peroxydisulfate without defluorination with a hydrazine treatment. PS-SWNT was found to be effectively cut by ozonolysis in a water suspension with preserved water solubility. Controlled by the electron dosage, a high energy electron beam (3MeV) has been demonstrated to cut ozonated SWNT. Besides ozonolysis, 700°C has been shown an optimal temperature to cut F-SWNT by pyrolysis in an argon atmosphere.