Abstract: A heat exchange device is provided whose exchange zone is formed by juxtaposing a plurality of plates parallel with each other and spaced apart two-by-two by a plurality of spacing elements consisting of spacers parallel to each other, which may be crenellated (they then comprise crenels and projecting parts) or continuous, said plates being formed so that for any two adjacent plates, at least one of the facing faces is provided with spacers, at least one part of said spacers being, over at least a part of their length, in contact with the facing face of the adjacent plate or with at least a part of the spacers possibly present on said facing face, over at least a part of their length, said plates, defining flow spacers for two fluids being further formed and disposed so that for one flow space out of two the spacers carried by at least one of the facing faces of two adjacent plates defining said space are crenellated spacers. The fluids flow advantageously in cross-current relation.