<PICT:0455567/IV/1> <PICT:0455567/IV/2> <PICT:0455567/IV/3> Acetylene is obtained by feeding a finely comminuted, normally solid carbonaceous material and a normally fluid hydrocarbon material simultaneously to an electric arc. The normally solid carbonaceous material must have an atomic H : C ratio below 0,75, and may be soft or hard coal, coke, charcoal or lamp black. The normally fluid hydrocarbon material may be methane, natural gas, petroleum refinery gases, ethane, butane, ethylene, butylene, naphtha, gas oil, or tar. The materials are preferably preheated, and may also be mixed before they are fed to the arc. The period during which the materials are subjected to the reaction temperature should lie between 1 and 0,0005 second. The process may be effected at atmospheric or somewhat raised or reduced pressure, and the reaction products should be rapidly cooled, e.g. by injection of water; the cooling water may be recirculated directly, or the solids which it contains may be separated and optionally returned to the arc. As shown in Fig. 1, coke or coal fed to a crusher 1 is passed by a blower 2 to a hopper 6, from which it is fed to a pipe 8 through which hydrocarbon gas is supplied. The mixture passes through a preheater 9 to an arc 10, the products from which pass through a water spray 14, cooler 15, dust separator 16 and blower 17 to a scrubber 18, from which the gases containing acetylene are withdrawn. The liquid used in scrubber 18 may be gas oil or other solvent for diacetylene and like impurities. The solids washed from the gases by the spray 14 are collected in a tank 20 and may be discharged through outlet 24 or fed by a conveyer 25 through a drier 26 and thence to blower 2. Clarified water from the tank 20 is returned to the spray 14 by a pump 28. In a modification, Fig. 2, the hydrocarbon gas is fed to the arc 10 through a hollow positive electrode 11a, and the solid carbonaceous material is supplied as a preferably preheated solid rod 30 fed against an abrading device such as a rotary toothed wheel or drum 31, preferably water-cooled; the products are withdrawn through the hollow annular negative electrode 12a. In a further modification, Fig. 3 (not shown), the positive electrode is solid, and a hydrocarbon liquid, e.g. gas oil, containing solid carbonaceous material in suspension, is fed through nozzles directly into the arc. In a further modification, Fig. 4 (not shown), a mixture of hydrocarbon gas and solid carbonaceous material is fed downwardly through a vertical hollow positive electrode and the products are cooled by a water spray immediately after they have passed through the negative electrode; alternatively, the materials may be fed tangentially into the arc chamber so as to produce a swirling arc. As a further modification, Fig. 5 (not shown), the arc may be struck between electrodes composed of finely divided carbonaceous material loosely packed in stick form, a hydrocarbon gas or vapour being fed to the arc through a preheater; the electrodes for use in this modification may be prepared by mixing coke dust with such a restricted amount of a binder that a shower of dust particles is produced in the arc; the binder may be water, preferably containing a little glue or like material, or a water-insoluble p binder such as tar; loosely packed rods prepared as described may alternatively be used merely as the source of solid carbonaceous material in association with ordinary carbon electrodes. Fig. 6 shows a further modification in which hydrocarbon gas is fed to an arc 10 through a pipe 8, and solid carbonaceous material is supplied as a rod 30 fed against a toothed wheel or drum 31. The Specification as open to inspection under Sect. 91 defines the solid carbonaceous material as having, preferably, a H : C ratio below 1, and specifies, as suitable materials, asphaltenes, polynuclear aromatic materials such as anthracene and fluorescein, or derivatives thereof or products containing them, such as suitable fractions obtained by the distillation of coal or oil shale. This subject-matter does not appear in the Specification as accepted.