A heat exchanger includes a heat exchanger housing with an exhaust gas inlet adapter and an exhaust gas outlet adapter, which encloses and bounds off a flow space for a coolant. The heat exchanger is furthermore configured with platelike heat exchanger elements arranged in parallel with each other and forming exhaust gas flow ducts, through which exhaust gas flows and around which liquid coolant flows. A heat exchanger element comprises two wall elements, which are joined together on opposite side surfaces and are configured with ribs on both surfaces. The ribs are arranged on an inner side and within the exhaust gas flow duct and on an outer side of the heat exchanger element. Adjacent heat exchanger elements arranged with outer sides facing each other are joined together at end faces abutting each other, forming a coolant flow duct having the ribs disposed therein.