It is reported that noble metals such as Pt, Pd and Rh can be used for CO conversion. Noble metal supported catalysts can remove CO at room temperature, but activity and stability is greatly influenced by the kind and characteristics of the carrier. Zeolites are the best catalytic carriers, characterized by a special crossed diporous structure, large specific surface area, good thermal stability, as well as the supported noble metal with the character of nanometer material. We report the removal of CO in mainstream smoke by a noble metal supported catalyst using a zeolite as the carrier. Research shows that a Pd/NaZSM-5 catalyst can effectively oxidize CO in a gas mixture at room temperature (18°C), and that activity of the catalyst varies with preparation conditions. For example, the higher the Pd loading the higher the catalytic activity, while a higher calcination temperature and larger Pd particle size reduces activity. Research results indicate that the CO content in smoke is decreased by nearly 20% without changing cigarette taste when a highly active catalyst is applied to the cigarette. This technology may be important for harm reduction strategies.