Selective decoration of Ag nanoparticles has been achieved on the defect sites of single-walled carbon nanotubes (SWCNTs) without causing damage to their tubular morphology. SWCNTs were purified using HCl treatment and thermal annealing process, which induced little functionalized or oxidized sites. The decoration of Ag nanoparticles was performed through η 2-coordination using Sn 2+ ions and reduction of Ag + ions on the defects of SWCNTs. Ag nanoparticles were deposited selectively and heterogeneously on the SWCNT bundles with a mean diameter of 4 nm. It is suggested that the defects of SWCNTs play a role of electron acceptor for the landing Sn 2+ ions.