This work provides better understanding on the nature of amorphous carbon nanotubes, which are synthesized via a simple chemical route. Amorphous carbon nanotubes (alpha-CNTs) are successfully synthesized by heating a mixture of ferrocene and ammonium chloride at temperature as low as 200 degrees C and are treated with hydrochloric acid. Transmission and field emission scanning electron microscopy techniques are performed to examine the morphology and dimension of the samples. X-ray diffraction tests confirm the amorphous structure of the nanotubes. The Fourier transform infrared spectroscopy and Raman studies indicate that the treated alpha-CNTs consist of many defective walls and are more amorphous compared with the untreated alpha-CNTs. Ultraviolet-visible absorption studies reveal that the untreated and treated alpha-CNTs exhibit plasmon absorbance with high bandgaps of 4 eV and 4.35 eV, respectively. (C) 2012 Elsevier Ltd. All rights reserved.