Carbon nanotube (CNT) is a breakthrough of cancer drug delivery which is able towards into targeted cells while minimizing normal cells damage apart from cancer cells. CNT has the ability for high anticancer drug loading and high targeting delivery without causing side effects. Functionalization process is required to elevate the dispersibility of CNT as a drug delivery due to the CNT limitation which not matched the standard of drug delivery system, such as dispersibility. This study aims to obtain the effect of hydrochloric acid (HCl) molarity optimization to the dispersibility of functionalized CNT (f-CNT). f-CNT is functionalized using a mixture of 6M HNO3 and 6M H2SO4. Variation were performed at HCl molarity which consist of 6M, 8M, 10M, and 12 M. The greatest HCl molarity is f-CNT which does not damage the morphology of CNT, has a high stability of dispersion, and impurities-free. Functionalized CNT (CNT-f) were characterized by Fourier-Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS), and dispersion tests. The characterization resulted f-CNT with HCl molarity of 10M has the greatest oxygen percentage with 6,84% dispersibility for more than 24 days.