Nanotechnology is the study of manipulating matter on an atomic and molecular scale. Generally, nanotechnology deals with developing materials, devices, or other structures possessing at least one dimension size from 1 to 100 nanometers.Â Carbon nanotubes have great potentials for novel applications in industry, drug delivery system and many other uses. In this work after purification, multiwall carbon nanotube was functionalized in acids by liquid phase oxidation method for drug delivery system. The structural and chemical changes after carboxylation of MWNTs improved the solubility and dispersibility of the carboxylated MWNTs in water. Fourier transformed infrared spectroscopy, and transmission electron microscopies were carried out for characterization of these methods of MWCNTs functionalization.