Three different types of Ru/MCM-41 catalysts were prepared by impregnating MCM-41, which had a high surface area of 1200 m(2) g(-1) and a very uniform mesoporous size of 27 Angstrom, with RuCl3 or Ru(OH)(3) or Ru-3(CO)(12). The catalysts were characterized by surface area and pore size distribution. The state of Ru and its dispersion on MCM-41 surface was studied by XPS and chemisorption, respectively. The conversion of nitrous oxide to nitrogen and oxygen, by catalytic decomposition and reduction reactions, was studied using the synthesized Ru/MCM-41 catalysts. The effects of the amount of Ru loading, the type of Ru precursor, catalyst pore size, as well as the presence of oxygen, carbon monoxide, and moisture in the feed stream on the catalyst activities for the catalytic decomposition and reduction of N2O were investigated. The results show that the Ru/MCM-41 catalyst prepared from Ru(OH)(3) as the catalyst precursor and having a 5 wt.% Ru loading is promising for the catalytic decomposition and reduction of N2O.