We report on the hydrophobic coating for multi-walled carbon nanotubes (MWCNTs) under low pressure as treated with toluene(C6H5CH3) glow discharge plasma. We investigated optimizing time and the hydrophobic surface of the treated MWCNTs. In order to identify a change of the properties about the toluene plasma modification for treatment of MWCNTs powder, which was observed putting the MWCNTs in the water and calculated via measuring the contact angle between the cushion of MWCNTs powder using the formamide, glycerol and water such as probe liquids. The produced carbonaceous species from the toluene glow plasma were identified by optical emission spectroscopy. Also, we conducted the experiments by varying times from 1 to 10 min and we found optimizing time. The total surface free energies were determined by the Owens-Wendt equation and drastically decreased from 72.90 mJ/m(2) to 0.79 mJ/m(2), respectively. (C) 2010 Elsevier B.V. All rights reserved.