A method for producing low-temperature coke in which each retort is a monobloc iron casting 9 ft (2.7 m) high, containing 12 tubes, which taper from 4-1/2 in (11.4 cm) at the top to 5-1/4 in (13.3 cm) at the bottom. A battery contains 36 retorts in 2 rows of 18. Retorts and combustion chambers are arranged alternately, so that each retort is located in a radiation chamber formed by the walls of adjacent combustion chambers. The retorts are heated only by radiation from these walls, so that there is no overheating and the inside temperature of the retorts can be maintained accurately at 1,112 degrees F (600 degrees C). A cooling chamber is fitted below each pair of retorts, of a size sufficient to hold the coke from both. The pairs of retorts are charged and discharged every 4 h.