Ammonia production characteristics were conducted on Ru/(MgO-CeO2) catalysts loaded on Ag-Pd-hydrogen-permeable membrane, in which the ammonia formation rate on the membrane reactor was more increased than that on conventional flow reaction. This result is responsible for the high reactivity of atomic hydrogen supplied from the Ag-Pd-permeable membrane to retard the hydrogen poisoning generally observed on Ru-based ammonia synthesis catalysts.