Protonated (H)-beta-alumina is a two-dimensional ion conductor in which conduction carrier is a proton which can move easily. In order to design active sites for the catalytic reaction, the role of the proton in the layer structure of the H-beta-alumina for the selective catalytic reduction of nitrogen oxide with propene was investigated. Following that, the catalytic activity of the H-beta-alumina was compared with that of the gamma-alumina. The H-beta-alumina showed much higher activity and selectivity for this reaction than the gamma-alumina. It was found that the H-beta-alumina possessed Bronsted acidity, although gamma-alumina shows Lewis acidity. It was shown that the acidic sites of the H-beta-alumina involved the protons in the conduction planes and by building up the conduction planes, the activity was successfully increased.