The surface modification of carbon nanotubes (CNTs) can be tailored to allow the formation of a complex between these potential carriers with DNA. In this chapter, protocols developed in our lab to prepare transfection vectors through the modification of MWCNTs are described. The protocol includes sections focused on the reduction of CNTs length, protocols to increase the dispersability of CNTs and finally, protocols for surface modification to attach through electrostatic interactions DNA to the CNTs.