Individually isolated single-walled carbon nanotubes (SWNTs) are coated with a monolayer of cationic surfactant to improve the stability of their dispersions in water. After polymerizing the counterions of the surfactant, the monolayer coating is “locked in” (see figure), and the SWNTs are redispersible even after harsh processing such as freeze-drying, offering improved potential for practical applications.