Amorphous carbon nanotube brushes were prepared by a simple method using glucose as the carbon precursor. The functional surfaces of these nanotubes were covered with gallium ions and then calcined to get gallium oxide nanotube brushes. The gallium oxide nanotube brushes were successfully converted to crystalline GaN nanotube brushes by treatment of ammonia at 800°C. The method is applicable to make other nanobrushes as well. © 2007 American Chemical Society.