A cooling plate for an iron and steelmaking furnace includes a copper cooling plate body having at least one cooling duct for a cooling medium extending essentially parallel with the back of the cooling plate body. The cooling plate body further includes a preformed, externally accessible recess into which the cooling duct opens. A connection piece is utilized as a cooling medium connection on the back of the cooling plate body, while a formed piece fitted within the externally accessible recess forms a deflection surface for the cooling medium flowing from the connection piece into the cooling duct, or from the cooling duct into the connection piece.