Experiments have been performed using a high-temperature membrane reactor to evaluate the relative performance of various composite membranes. Two membrane categories (porous and dense) and three types of composite membrane systems (Pd/Ag, silica and Pd-dispersed porous) have been studied and their performance compared. Also considered is the special case of the Pd-Ag composite system having imperfections. The industrially important reaction of propane dehydrogenation over noble metal catalysts to produce propylene was selected for study. Results have been obtained which indicate that the dense Pd-Ag composite system does possess higher performance levels in the temperature range studied. However, metal-dispersed porous systems have advantages due to their significantly higher contact surface-to-volume ratio. High hydrogen permselectivity is confirmed as a key factor in determining reactor performance in terms of conversion enhancement.