The present invention relates to a heat exchanger (1) for the exchange of heat between a first fluid and a second fluid, the said heat exchanger (1) comprising an exchange bundle (15) and a housing (11, 20) designed to encase the said exchange bundle (15), in which the heat exchanger (1) is provided with an inlet (16) and with an outlet (17) which are intended for the first fluid, and with an inlet (21) and with an outlet (22) which are intended for the second fluid, characterized in that the housing (11, 20) is made up of an essentially planar or, for preference, planar, first part (11) in the form of a plate designed to form one wall of the said housing, and of a receptacle-shaped second part (20), the said second part (20) having a free edge (25) designed to be connected to the said first part (11) and thus form the said housing (11, 20).
