We describe herein strategies for one pot synthesis of diazonium salts followed by immediate reaction with hydrogen peroxide for SWCNT functionalization. The previously described superacid mediated aryl functionalization of SWCNT benefits from the ability to generate diazonium salts in situ, via reaction between anilines and sodium nitrite. These diazonium-forming reactions are typically performed in concentrated acids, and so are unsuitable for our peroxide-mediated reaction, which favors neutral pH conditions. We have therefore developed a modified strategy for in situ diazonium formation compatible with our peroxide-mediated chemistry, facilitating a one-pot functionalization strategy. 4-Nitroaniline, 3,4,5-trifluoroaniline, and sulfanilic acid (Figure ) were individually reacted with nitrosyl tetrafluoroborate (NOBF4) in water. NOBF4 reacts with water to generate nitrous acid, which in turn oxidizes the aniline to diazonium. (GT)15-SG65i SWCNTs were added in PBS, neutralizing the residual nitrous acid. Hydrogen peroxide was then introduced to initiate aryl functionalization. As shown in Figure , functionalization then proceeded as with the previously described peroxide-mediated functionalization reactions. In the case of 4-nitroaniline, the resultant E11 -peak was found at approximately the same wavelength as SWCNTs functionalized directly using NO2PhN2-BF4 (1159 nm, Table , Figure ). By generating diazonium salts in situ from anilines, it is potentially possible to functionalize SWCNT with diazonium salts which are only transiently stable.