Abstract: A heat exchanger comprises a set of plates defining between them circuits for a fluid flowing alternately via seals mounted between each pair of two adjacent plates. Each plate including at least one guiding cut formed at least at one of the ends thereof for guiding each plate inside a frame. The exchanger also includes between each pair of two adjacent plates, and in proximity to the guiding cut, at least one strut to be compressed and in contact with the two adjacent plates. Each strut has, before compression, a thickness at least equal to that of the seal.