Abstract: In a steam reforming valve having pressure-reducing valve means for reducing the pressure of superheated steam at high temperature and high pressure and temperature reducing means for reducing the temperature of said superheated steam by spraying water thereinto, a perforated plate comprises a part fixed to a main structure of the steam reforming valve on the downstream side of the temperature reducing means with respect to the direction of flow of the steam within the main structure and a disc part held by the fixed part and having a plurality of through-holes for passing therethrough steam and sprayed water. The disc part is of a construction whereby it has a free end relative to the fixed part.