the present invention provides a powerful new method for producing , uniform sized and uniformly aligned nanotubes through catalytic pyrolysis of a hydrocarbon within the dense , uniform and parallel pores of alumina nano - templates . the catalyst , co , fe , ni or another suitable substance is deposited electrochemically into the bottom of the channel of the alumina template . the nanotubes with any desired diameter in the range 5 - 500 nm and lengths up to ˜ 100 μm , are generated by the pyrolysis of a suitable hydrocarbon inside the pores of the alumina template with at least one end open at the alumina / air interface . the nanotubes may be filled by metals using for example electroless deposition .