Abstract: A heat exchanger plate of single unitary structure and relatively thin material has a deep draw formed through one surface adjacent to each of the opposite ends to provide fluid openings and a lesser depth inner draw formed in the other surface to provide a fluid passage communicating with the fluid openings. The plate is adapted to oppose adjacent plates in a stacked configuration to provide heat transfer between separate fluids flowing through counterflow passages on opposite sides of the plate. The recessed area on one surface of the plate forms a fluid passage with its adjacent plate in the stacked array for flow of a first fluid through the stack from side to side of an enclosing housing. A collar formed around each plate opening by the deep draw is adapted to nest with a corresponding collar of an adjacent plate to provide manifold sections communicating with a second fluid passage.