Mesoporous MoO3 shows an apparent activity in the catalytic hydrogenation of N-ethylcarbazole (NEC), where a significant amount of tetrahydro-N-ethylcarbazole (4H-NEC) and perhydro-N-ethylcarbazole (PNEC) are detected with the hydrogen uptake of 0.97 wt% after 6 h when the temperature rises to 220 degrees C. 0.5 wt% Pd/MoO3 catalyst shows a superior catalytic efficiency than the traditional precious metal catalysts 0.5 wt% Ru/Al2O3 and 0.5 wt% Pd/Al2O3, especially in the conversion of Octahydro-N-ethylcarbazole (8H-NEC) to PNEC. The hydrogenation mechanism of MoO3 is completely different from the traditional precious metal catalysts. With the presence of a small amount of Pd, the breaking of H-H bond is greatly accelerated, result in the promotion of hydrogen spillover rate and the increase of the concentration of hydrogen molybdenum bronze HxMoO3, which improves the catalytic efficiency of the MoO3 catalyst. Rise the temperature also helps increasing the concentration of H in HxMoO3. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.