Abstract: A recuperative heat exchanger having a heat exchamber core composed of a plurality of spaced apart plate members is disclosed. The core is disposed for receiving high temperature exhaust gases. A case member is positioned around the heat exchanger core. The case member has an exhaust gas inlet opening and an exhaust gas discharge opening. The plates of the core are secured to the case member at the exhaust gas inlet opening. A jacket is positioned in a spaced apart relationship around the case member. The jacket has an intake opening and an exhaust opening. The intake opening of the jacket is in alignment with the exhaust gas inlet opening of the case member and the exhaust opening in the jacket is in alignment with exhaust gas discharge opening in the case member. The case member is secured to the jacket at the exhaust gas discharge. The core and case member of the heat exchanger are capable of expansion and contraction in the jacket during the operation of the heat exchanger.