Amorphous carbon nanotubes (alpha-CNTs) have been synthesized by heating a mixture of ferrocene and ammonium chloride at a low temperature of 200 degrees C. Surface morphological studies reveal that the as-prepared nanotubes are straight tubular structures with open ends. The Raman spectra reveal the presence of defects in the nanotubes. Both chemical oxidation and hybridization treatments result in hybridization between alpha-CNTs and cadmium selenide quantum dots (CdSe QDs), giving an increase in the average outer diameter, surface roughness and the number of defects for the alpha-CNTs. The decreasing outer diameter size of nanotubes reduces the permittivity contribution in overall due to size quantization effect. Chemical functionalization initiated by the oxidation and attachment of CdSe QDs due to hybridization improve the dispersion stability and permittivity of alpha-CNTs. The alpha-CNTs-CdSe QD hybrids have the potential for electromagnetic and microwave absorption applications as they exhibit a high imaginary component of permittivity (dielectric loss). (C) 2012 Elsevier B.V. All rights reserved.