The efficiency of the partial oxidation of propene (PP) to propylene oxide over a Cs-Ag and a Re-Ag catalysts immobilized in two porous ceramic tube membrane reactors (designated Cs-membrane and Re-membrane respectively) was compared by using three different flow reactors (convection flow (CFR), diffusion flow (DFR) and plug flow (PFR) reactors). In the Cs- and Re-membranes, the CFR was commonly designed as the best efficient reactor at 420524 K and, as a common reaction kinetics, two steady state rate equations. for the production of propylene oxide (PO) and CO, were separately proposed by two different reaction pathways. The reactor efficiency of CFR for the PO production selectivity was evaluated as 11.2-17.5% for the Cs-membrane reactor and 18-75% for the Re-membrane reactor because of an advantage of PO production rate constant as a rate determining step, which was effectively regulated by the amount of a stable intermediate formed on the catalyst surface in a CO2 formation pathway.