As a pre-treatment step for ultra deep hydrodesulfurization (UD-HDS), sulfur and nitrogen species were adsorptively removed from the straight run gas oil (SRGO) over activated carbon materials. An activated carbon having the largest surface area and highest surface polarity showed the highest total capacity for adsorption of sulfur and nitrogen species as 0.098 g sulfur and 0.039 g nitrogen per 1 g of the activated carbon, respectively, among the carbon materials examined. Removal of both nitrogen and sulfur species was found very effective to achieve UD-HDS under conventional HDS conditions. SRGO treated over activated carbon contained only 11 ppm of sulfur, while non-treated SRGO contained still 193 ppm of sulfur in its HDS product. (C) 2004 Elsevier B.V. All rights reserved.