The hydrogenation of a-methylstyrene (AMS) was carried out in a flow-through membrane reactor at.: 45-50 degrees C, 1-40 bar, and 18 vol % AMS in heptane. An alpha-Al2O3 membrane tube of defined pore size was used as catalyst support material. A wet impregnation method was used to prepare the active membrane with palladium as catalyst. Experiments with a spherical Pd/Al2O3 egg-shell catalyst in a slurry reactor were carried out under similar reaction conditions for comparison. Results from the flow-through membrane reactor were also compared to results from other types of reactors described in the literature. Application of the flow-through membrane reactor exhibits an enhanced performance with respect to the productivity (reaction rate per mass of palladium) relative to that of other types of membrane reactors and other conventional reactors, such as a slurry reactor, a trickle-bed reactor, and a bubble-column reactor. (c) 2006 American Institute of Chemical Engineers AlChE J, 52: 2805-2811, 2006.