Analysis of the kinetics of the hydrogenolysis of n-butane on a Ru/Al2O3 catalyst permits recognition of the range of H-2: n-butane ratio where carbon formation can be neglected. Variation of the apparent activation energy with H-2 pressure results from a variable contribution of its heat of adsorption to the true activation energy. Effects on product selectivities and on response of rate to H-2 pressure due to oxidation and low-temperature reduction are also traced to differences in heats of adsorption.