Abstract: This invention relates to a process for the preparation of a substrate-free aligned nanotube film, comprising: (a) synthesizing a layer of aligned carbon nanotubes on a quartz glass substrate by pyrolysis of a carbon-containing material, in the presence of a suitable catalyst for nanotube formation; and (b) etching the quartz glass substrate at the nanotube/substrate interface to release the layer of aligned nanotubes from the substrate. The invention also provides a process for the preparation of a multilayer carbon nanotube film comprising depositing a substrate-free carbon nanotube film onto another nanotube film. Further, the invention provides a process for the preparation of a “hetero-structured” multilayer carbon nanotube film which includes one or more carbon nanotube layers together with layers of other materials, such as metal, semiconductor and polymer.