The effects of thermal treatments and palladium loading on sorption characteristics of single-walled carbon nanotube (SWCNT) samples were investigated. The thermal treatment experiments were carried out in a temperature range of 300-800 degrees C. The sorption characteristics of nitrogen and hydrogen on the original, heat treated and the palladium loaded samples were investigated. Analyzing the nitrogen adsorption isotherms on these samples at 77.4 K, the highest specific surface area of 2230 m(2)/g was obtained at 575 degrees C, while the original samples had a specific surface area of 230 m(2)/g. The highest surface area samples obtained at 575 degrees C were loaded by 3.3, 6.3 and 10.1 wt% palladium and hydrogen adsorption isotherms on these samples were obtained at 77.4 K. The hydrogen sorption capacities of the original and the 10.1 wt% palladium loaded samples were found to be 0.76 and 1.66 wt%, respectively. it was shown that by controlling the temperature of heat treatment, the specific surface area of the samples could be increased and the spillover effect of palladium could enhance the hydrogen sorption. (c) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.