At present study, platinum doped MCM-41(Si/Al=40) catalyst, which has been widely used as a new type of meso-porous catalyst, was tested for the reduction of NO_x with propylene as reducing agent. In order to confirm the structure, various characterization techniques such as XRD, N₂ adsorption-desorption isotherms, NO-TPD, and BET surface area measurements were performed. Also, by using a simulated flow gas mixture, NO reduction activity test was carried out on various kind of catalyst such as Pt/MCM-41, Pt/Al-MCM-41 and Pt-ZSM-5. The general trends of activity measurements showed that the maximum NO conversions appeared at relatively lower temperature region(low than 250℃) probably due to the existence of Pt on support. This is supported by the existence of larger peaks at lower temperature region from TPD pattern, when compared with that of MCM-41 only. Specially Al exchanged MCM-41 showed the best NO conversion activity than others. It is speculated that the exchanged Al sites give rise to additional active site for NO adsorption, because Al-MCM-41 shows a larger hystersis loop in adsorption-desorption isotherms. 10 vol wt% water was added to the stimulated folw gases, but the NO conversion activity was not changed significantly on Pt/Al-MCM-41. Therefore, newly proposed Pt/MCM-41 catalyst might be a better candate for the practical use in SCR process using propylene than on conventional Me-ZSM-5 catalysts.