A new convenient room-temperature template-free route for high-yield synthesis of double-walled bismuth nanotubes through the treatment of solid bismuth monoiodide with n-butyllithium is presented. Scanning electron microscopy and transmission electron microscopy observations of the product show uniform one-dimensional nanoparticles with high aspect ratios and lengths up to several hundred nanometers. Investigations of the cross sections of the bismuth nanotubes reveal an inner diameter of about 4.5 nm and an outer diameter of 6 nm. The tube walls consist of two coaxial cylinders, and the estimated thickness of the double-wall of about 0.75 nm matches quite properly two layers in the rhombohedral bismuth bulk structure.