Covalent functionalization could help dispersion of multiwalled carbon nanotubes (MWCNTs) in polymeric matrices to explore their exceptional properties on several nanotechnology applications, from medicine to engineering. In this work, the surface functionalization of three types of MWCNTs were performed using the active group 4-[(N-Boc)aminomethyl]aniline. The aniline reacts with the MWCNTs as the aliphatic amine is protected with tert-butyloxycarbonyl (Boc), afterwards the Boc group is removed leaving the free amine and confirmed by the colorimetric Kaiser Test .TGA analysis of the functionalized MWCNTs, under nitrogen atmosphere, presented loss of mass in the region of 200 to 400°C related to the Boc protected benzylamine. Raman spectroscopy showed an increase in the D band, the disorder-induced mode, attributed to the structural alterations of the outer layer of the MWCNTs due the formation of covalent bonds between carbon and phenyl ring.