This work presents energetics for high pressure hydroprocessing reactions derived from post analyses of liquid and gaseous products. Specifically, GC and GC/MS were used to follow the product distribution fram the hydrocracking of methyldecalins over zeohte supported palladium and platinum catalysts as a function of temperature. Plain Arrhenius plots summarize key results and reveal possible connections in terms of`activation energies between hydrogen consumption and the amounts of different products. The total cycloalkane production and the consumption ofhydrogen both show a simple temperature dependence with the same{open_quote}activation{close_quote} energies. Methane production varies more rapidly with temperature but can still be described by a single exponential term. The final example, conversion to aromatics, displays a more complicated dependence with an accelerated yield at high temperature. This form of data analyses connects to a new routine for mass balance evaluations and it is now applied to model catalyst performance and to understand optimum reaction conditions. Other branches of this project include surface spectroscopic measurements of fresh, sulfided and used catalysts, characterization of partially hydrogenated naphthalenes and modeling of hydrogen activity at metal sulfides.