Hydrogenation of six model feeds containing three-, two-, and one-ring aromatic compounds was investigated to gain insights into the aromatic hydrogenation reaction chemistry over a commercial NiMo catalyst under practical reaction conditions. The hydrogenation reactivity of the aromatic compounds followed the following order: phenanthrene similar to two-ring aromatics >> one-ring aromatic. Comparison with previous studies revealed that the relative reactivity of the aromatic compounds is strongly influenced by the nature of the catalyst. Multiple-component feed studies showed that phenanthrene and naphthalene strongly inhibited the tetralin hydrogenation rate; however, naphthalene and tetralin had no appreciable effect on phenanthrene conversion. Langmuir-Hinshelwood-type rate equations were used to describe the reaction kinetics with physically meaningful and well-identified parameter values. The inhibition was attributed to competitive adsorption and was described in the kinetic model by adsorption terms that were obtained from the multicomponent feed experiments.