Single-walled carbon nanotubes (SWNT) polarize readily in the presence of electromagnetic (EM) fields, enabling a variety of electrochemical reactions. Here, we study the reaction of transition metal ion salts in the presence of surfactant-stabilized SWNT individually suspended in water when activated by alternating EM fields in the radio frequency (RF), microwave (MW), and optical regimes. Atomic force microscopy (AFM) images show formation of novel SWNT nanoparticle−nanotube structures (nanoPaNTs). The resulting nanoPaNTs include SWNT with metallic nanoparticles at one or both tips (“dumbbells”), SWNT toroids, and straight SWNT “threaded” through multiple SWNT rings to form shish-kebab structures. Mixtures of surfactants and polymer apparently modify the local environment of polarized SWNT in a manner that reduces the energy needed for ring formation. We also infer that electrodeposition reactions proceed on a significantly faster time scale than ring formation. These processes can potentially be used for self-assembly of complex 3-D structures.