Keywords: multi-walled carbon nanotubes (MWCNT), iridium-doped, nanohybrid composite, Raman spectrum, energy-dispersive X-ray spectroscopy Multi-walled carbon nanotubes have been prepared by chemical vapour deposition pyrolysis of ethyl alcohol at 665°C. The addition of atoms other than carbon to the nanostructure, in our case the iridium component, leads to the formation of defects that contribute to changes in the electrical and optoelectrical properties. The formation and structural changes of multi-walled nanotubes were studied using an electron microscope, Raman and energydisperse spectrometry. Using the Raman and X-ray spectrum, a clear difference between the synthesis without and with the addition of iridium impurities was found.