So-called “anode activation” is shown to entail the growth of metallic fibers with nanometric dimensions. These fibers grow from dendritic deposits comprised of carbon and chromium, and thus chromium is a major component. They are confined inside thin-wall carbon nanotubes, with their diameter defined by the inner diameter of the host nanotube. This growth behavior reflects a template-mediated type of fiber growth. ©1997 American Institute of Physics.