The poisoning effects of two types of carbon-containing sulfides (CS2 and CH3SSCH3) on Ni/Al2O3 catalysts for the hydrogenation of benzene and cyclohexene were systematically investigated via experiments and DFT calculations. The toxicity of CH3SSCH3 is two and three times greater than that of CS2 for the hydrogenation of cyclohexene and benzene, respectively. The characterization and DFT results reveal that CH3SSCH3 dissociates easily during hydrogenation and releases CH4, allowing sulfur atoms to poison the Ni sites. However, the presence of CS2 in the hydrogenation step slows the decline in the catalytic performance, because of resistance to the direct dissociation of the strong C=S bond of CS2. The chemisorbed CS2 molecules and their incomplete dissociation weaken the strength of Ni-S bond and decrease the poisoning effect of sulfur. The poisoning processes of two sulfides are also discussed following a DFT study. This work opens up promising possibilities for the industrial study of S-poisoning resistance in supported Ni catalysts. (C) 2017 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.