Abstract: The heat exchanger is for cooling air by using water, particularly for use as an intercooler in an internal combustion engine. The heat exchanger has an elongate core assembly housed within a shell. The core assembly has a plurality of spaced apart tubes extending between an air inlet and an air outlet; a plurality of flow conduits disposed between and in thermal contact with the tubes, the flow conduits passing water across the core assembly generally at right angles to the air flow to transfer heat between the tubes and the water; and baffles disposed so that water enters the core assembly by a water inlet and propagates through the core assembly generally in the direction of the air flow axis along a tortuous path, along which the water absorbs heat from the tubes to cool the air, and exits through a water outlet.