Abstract: A blackbody type heating element for calibration furnaces employs an elongated hollow cylinder of graphite open at first and second opposite ends. The cylinder has an integral solid graphite partition centrally disposed in the cylinder and oriented at right angles to an axis of elongation of the cylinder. First and second end caps are disposed adjacent corresponding ones of the first and second cylinder ends. Each cap has a first electrically conductive member adapted to be connected as an electrode to a suitable source of electrical energy and a second graphite type hollow cylindrical member open at both ends engaging the first member. The second member has a coating of pyrolytic graphite. Each second member is connected directly through its coating to the corresponding end of the cylinder. The openings in the second member are aligned with this corresponding end.