A process can be used for performing a pyrolysis of hydrocarbons in a rotary drum reactor at a temperature in the range of from 600 to 1800° C. The heat for the endothermic pyrolysis is provided by resistive heating of at least one particulate electrically conductive material introduced into said rotary drum reactor and moved through the rotary drum reactor with a flow of a hydrocarbon. The rotary drum reactor contains (A) an inner wall made of electrically insulated material, (B) a pressure-bearing outer wall, and (C) an electrical heating system attached to the inner wall and/or at least one integrated electrically conducting electrode pair. The at least one electrode pair is located at both ends of the inner wall of the rotary drum.