Abstract: An exhaust gas re-circulation cooler device comprises at least one cooling plate, said cooling plate comprising an upper plate wall and a lower plate wall; said upper and lower plate walls defining a plurality of gas passages which have a gas inlet at a first end of cooling plate and a gas outlet at said first end of said cooling plate; each said passage directing a gas flow between said inlet and said outlet and along a length of said plate; and said plate being sealed so as to be gas tight along a length of said plate, and at a second end of said plate.