Abstract: Development of monolithic catalyst is vital for the treatment of high flow exhaust gas generated in large nuclear facilities. Herein, a new method including zeolite washcoat growth on cordierite monolith followed by ion exchange of Pt was reported. The obtained monolithic Pt/zeolite catalyst possesses high metal dispersion(60%). At 15 ℃ and 1.0% H₂, a conversion of >99.9% is achieved with a gas hourly space velocity(GHSV) of 10 000-40 000 h^-1 over the monolithic Pt catalyst, and complete conversion is achieved with a GHSV of 50 000 h^-1 at 25 ℃ and 1.0% H₂. At 0.1% H₂ and 0.5% H₂, the catalytic activity is lower in wet conditions than that in dry conditions because the water vapor can inhibit the room temperature catalytic activity. Since the zeolite coating has lower water absorption capacity than Al₂O₃, the hydrogen conversion over monolithic Pt/sil-cord remains 80% at 0.1% H₂ while the conversion over monolithic Pt/Al₂O₃ is only 13%. Thus the monolithic Pt/zeolite catalyst shows obvious steam-tolerance.