A fundamental Langmuir-Hishelwood-Houegn-Watson kinetic model for the hydrogenation of monoring aromatics over Pt catalysts was constructed, based on detailed first principles density functional calculations. The model parameters were obtained from the first principles calculations and from statistical mechanics. The first principles based kinetic model rather accurately described laboratory scale kinetic data for the hydrogenation of toluene over a 0.5 wt % Pt/ZSM-22 catalyst. The incorporation of this kinetic model in the simulation of an industrial hydrocracker revealed effects such as hot spot formation and liquid phase hydrogen depletion near the entrance of the reactor. For the highest aromatic content, i.e., higher than 15%, a regime was established in which the interphase hydrogen mass transfer became rate limiting. This was evident from the development of a shoulder in the liquid phase temperature profile and from the delayed recovery of the liquid phase hydrogen flux from the initial depletion. This is an abstract of a paper presented at the AIChE Annual Meeting and Fall Showcase (Cincinnati, OH 1/04/2005).