The rate of redistribution of 14C between benzene and cyclohexane has been investigated over supported Au catalysts, in the temperature range 200 to 250 °C, partial pressures of ~0.2 atm, and total pressure 1 atm. The catalyst variables studied were the Au concentration, 0.3 to 5 wt %, and the catalyst support, Al2O3, MgO. Two methods of catalyst preparation were employed. In one, Au particles were formed by low temperature (~100 °C) chemical reduction, while in the second method by thermal decomposition of the Au salt at higher temperatures. Diameter of the Au particles ranged between 40 to >1600 Å depending upon the type of support and preparative method. From the experimental results the reaction rate constant and the analytical relation between the ratio cyclohexane/benzene and reaction rate were determined. Rate constants of the order of (1 to 10) × 10−6 [mole/g(cat)sec] were calculated. The analytical relation between the cyclohexane/ benzene ratio and the reaction rate was found to change for values of the ratio ≈3. The extent of the available metal surface per weight of metal was found to influence the reaction rate constant. This intrinsic surface effect was detected under conditions such that the molecular mean free path of reactants and products was large in relation to the diameter of the metal particle. It is suggested that whenever particle size and molecular free path are of the same order of magnitude, surface effects do not lend to easy detection. The general picture of the reactivity of surfaces of finely dispersed Au toward hydrogen and oxygen is compared.