In this review, recent progress on palladiumbased membrane reactors (MRs) is outlined concentrating on the production of pure hydrogen. Various aspects are presented concerning some dehydrogenation reactions as well as an analysis of the palladium based membranes under study and the governing equations. Some critical aspects of non-palladium based membranes are presented. Moreover, some problems related to the effect of contamination of the Pd-based membranes and to the H 2 flux are introduced; the long-term durability problems of inorganic MRs are also discussed.