A mounting assembly for an exhaust gas catalyst includes a metallic exhaust gas catalyst carrier body and a tubular jacket in which the catalyst carrier body is disposed. The catalyst carrier body is fastened to the tubular jacket while permitting lengthwise expansion of the catalyst carrier body, through the use of beads encircling at least part of the catalyst carrier body and corresponding formations formed in the tubular jacket into which the beads protrude in the form of slots and keys. The catalyst carrier body and the beads are disposed at axial and radial distances from the tubular jacket and the formations.