Photolysis of cyclic disulfides with single-walled carbon nanotubes led to a sidewall modification of the surfaces to introduce sulfur-containing functional groups, as confirmed by means of Raman, XPS, FT-IR, mass, and UV-vis-NIR measurements. A subsequent treatment of sulfur-containing substituents modified SWNTs with gold nanoparticles gave an attachment of gold on the surface of SWNTs through thioalkylthiol linkage.