A gas turbine engine recuperator including exhaust passages providing fluid flow communication between an exhaust inlet and an exhaust outlet, the exhaust inlet being oriented to receive exhaust flow from a turbine of the engine and the exhaust outlet being oriented to deliver the exhaust flow to atmosphere, the exhaust inlet having a smaller cross-sectional area than that of the exhaust outlet, and a cross sectional area of each exhaust passage progressively increasing from the exhaust inlet to the exhaust outlet such as to diffuse the exhaust flow. Air passages are in heat exchange relationship with the exhaust passages and provide fluid flow communication between an air inlet and an air outlet designed to sealingly engage respective plenums of the gas turbine engine.