Liquid phase hydrodearomatization (HDA) of monoaromatic model molecules (toluene, indane, tetralin, cyclohexylbenzene, nonylbenzene) from naphtha and middle distillate was conducted at a temperature of 170 A degrees C and a pressure of 100 bar over Ni/Al2O3 in order to compare their reactivity separately and in mixture. A reactivity scale was established where toluene is more reactive than tetralin, indane, cyclohexylbenzene and nonylbenzene. The difference of reactivity is due to steric hindrance of the substituent and its electronic effect. In all cases, the fully hydrogenated product is the main product. Toluene hydrodearomatization is inhibited by the presence of another monoaromatics. This inhibition effect is more significant with indane than with cyclohexylbenzene and nonylbenzene and tetralin corresponding to competitive adsorptions and highlighted by kinetic modeling. [GRAPHICS] .