First principle calculations were carried out to study the adsorption energy of dibenzothiophene and its alkyl derivated on functionalized surfaces of carbon nanotubes. The modified surfaces supported functional groups containing oxygen, i. e. hydroxyl, carboxylic and cetone groups. Dibenzothiophene and its alkyl derivates form hydrogen bonds between the sulfur atoms and the hydrogens of the functional groups containing oxygen atoms of the funtionalized nanostructures. The oxygen atom also forms hydrogen bonds with some hydrogens of the organosulfur molecules. The adsorption energy and bond separations were calculated and compared between the organosulfur molecules. The nature of the physical bond between the organosulfur molecules and the carbon nanotubes were studied in terms of the electronic density analysis.