<p>A catalytic reactor is provided with a pair of flat wall plates placed in opposition with a prescribed spacing so as to form a fluid flow path, a channeling member bonded to the flat wall plates so as to divide the fluid flow path into channels, and catalyst supports inserted into the respective channels and extending through the channels. At least one flat wall plate among the pair of flat wall plates is brought into contact heat-exchangeably with a temperature medium having a temperature range different than that of the inside of the flow path and thereby serves as a primary heat transfer surface. The cross-section of each of the channels has an aspect ratio (W/H) of the width (W) to the height (H) of not more than 1, and each catalyst support is comprised of a base member having a corrugated single layer structure, and a catalyst layer formed on the surface of the base member.</p>
