We present the results of Raman and field emission studies of the structural and physical features of iodine intercalated bundles of single-walled carbon nanotubes (SWNTs). The periodicity of hexagonally closest-packed pristine nanotubes was destroyed by the intercalation of iodine molecules in interstitial sites of carbon nanotube bundles. The Raman spectra obtained using a 647.1 nm line of Kr-ion laser indicate that I₂ intercalation does affect the electronic state of metallic SWNTs of small diameters of ∼1.26 nm changing into the insulating state. The turn-on electric fields obtained from the I–V measurements for iodine intercalated SWNTs and pristine SWNTs were 2.43 and 3.41 V μm⁻¹, respectively, and iodine intercalated SWNTs show higher field emission than pristine SWNTs do.