A process for producing hydrogen and pyrolytic carbon from hydrocarbons may involve converting hydrocarbons into hydrogen and carbon in a reactor at temperatures of 1000° C. or more. The reactor may include two electrodes spaced apart from one another in a flow direction of the hydrocarbons. In a region of the reactor between the electrodes an inert gas component is supplied over an entire reactor cross section. The reactor contains carbon particles in the region between the two electrodes. By introducing an inert gas component over the entire reactor cross section, deposition of carbon in this region of the reactor inner wall is prevented, thus effectively inhibiting the formation of conductivity bridges on the reactor inner wall.