After treated in a flow of H-2 at 500 degreesC for 60 min, CNTs showed moderate sign of hydrogenation. Intense hydrogenation of CNTs occurred under similar treatment when 1 wt.% of Pd was supported on CNTs. In situ FTIR investigation of NO (5000 ppm) interaction with hydrogenated CNTs showed the gradual removal of hydrogen from the sample. Surface adspecies such as OH, NO, NO2, and NO3 were observed over the hydrogenated 1 wt.% Pd/CNTs sample after the sample was exposed to pure NO at 500 degreesC for 15 min. The results suggest that the Pd metal catalyzes the hydrogenation of CNTs, and NO reduction occurs over the hydrogenated CNTs. (C) 2004 Elsevier B.V. All rights reserved.