Abstract: An annealing oven for wire and the like includes a tubular elongated heater made of electrical resistance alloy material. The wire passing therethrough is so guided that it remains at all times out of contact with the heater and no current passes through the wire. Relatively movable sections of heat-insulating material laterally jacket the tube to facilitate threading a wire through a slot in the tube and so as to facilitate rigid heating with a minimum of heat loss, so as to adjust heat loss as a part of temperature control, and so as to effect rapid cooling of the tube. The sections are arranged in pairs, and a pair of such sections has a lesser insulating capacity than the preceding section, taken in the direction of wire movement. The device is compact and takes a minimum of space adjacent to any material processing machine.