Electrochemical nitration of self-assembled single wall carbon nanotube (SWNT) sheets with -NO2 groups is reported. A SWNT sheet, used as the working electrode in 6 M aqueous solution of potassium nitrite, was anodically oxidized to form -NO2 groups on the SWNTs. Attenuated-total-reflection Fourier-transform infrared and micro-Raman spectroscopy showed the presence of chemisorbed -NO2 groups consistent with transmission electron microscope images of the nanotube bundles after functionalization. Approximately 13% weight loss attributed to C-NO2 bond breaking was measured by thermogravimetry, corresponding to an endothermic dissociation process measured by differential thermal analysis with an onset temperature near 425 ° C. © 2005 Elsevier B.V. All rights reserved.