The reinforcement of regulations for the production of cleaner fuels along with the larger demand for energy urge us to optimize the HDS processes. The transformation of various olefins alone and in mixture with sulfur compounds was investigated over a CoMoS/Al$_2$O$_3$ catalyst under HDS of FCC gasoline operating conditions. A reactivity scale was established with hex-1-ene being more reactive than 4-methylpent-1-en was more reactive than 4-methylpent-1-ene, 3,3-dimethylbut-1-ene and 2,3-dimethylbut-2-ene. The transformation of these olefins involves two main reactions ie isomerization and hydrogenation. In the presence of sulfur compounds (3methythiophene and benzothiophene), a mutual inhibiting effect was observed with benzothiophene 3,3dimethylbut-1-ene being respectively the most inhibiting sulfur and olefin compounds. These results were explained with a unique kinetic model from which the adsorption constants calculated were the highest for benzothiophene and 3,3-dimethylbut-1-ene.