A device for conditioning the flow of hot gas in a catalytic combustor in preparation for entry into a catalytic reactor. The device is composed of at least one and most preferably two or more disks that are secured to a shroud so as to be disposed in a plane generally perpendicular to the hot gas flow direction. Each disk is composed of a plurality of small cells oriented so that flow channels therethrough are axially disposed. The cells linearize the gas flow and exert drag on the gas flow therethrough. This generates a static pressure gradient in the flow fields upstream and downstream of the honeycomb disk, which in turn causes flow adjustments so as to produce a more uniform axial flow field. This results in a more uniform fuel/air concentration distribution and velocity distribution at the catalytic reactor inlet.