Abstract: An improved rod-baffled heat exchanger in which the tube bundle thereof comprises a plurality of tubes supported intermediate their ends by at least one outer support ring and a plurality of baffle rods carried by the outer ring and extending between parallel tube rows. The baffle rods are movable from a first position wherein the tubes adjacent thereto are loosely supported by the rods to facilitate assembly, to a second position wherein the tubes are firmly engaged and radially supported by the rods. Various novel forms of baffle rods are disclosed along with a novel method of construction of the improved heat exchanger.