Abstract: The volumes of hot gas required for use in certain large scale chemical processes may be heated to e.g. above 2500.degree. C by means of a distributed electrical discharge in an apparatus in which the supply of gas to a heating zone is through a plurality of adjacently positioned conduits arranged to constrain the gas at its point of entry thereto into a plurality of parallel streams and in which a plurality of electrodes are positioned respectively in the plurality of gas streams. If the dimensions of the conduit and of the electrodes are suitably controlled relative to the quantity of gas the distributed discharge may be maintained in the absence of seed or of a flame thus avoiding a source of contamination of the heated gas.