An ultrathin coating of individual multi-wall carbon nanotubes with germanium oxide was developed. Coated carbon nanotubes were prepared by in situ gelation of tetramethoxy germanium, forming an amorphous germanium oxide layer. The resulting germanium oxide/carbon nanotube nanocables were characterized by transmission electron microscopy (TEM), TEM/energy-dispersive x-ray spectroscopy, x-ray photoelectron spectroscopy (XPS) and current-voltage measurements. The approximately 10 nm thin germanium oxide layer provides excellent electrical insulating properties for individual carbon nanotubes.