Abstract: A method and arrangement of crosslinking or vulcanising an elongate element in which method a conductor element is coated by a layer of crosslinkable synthetic material in an extrusion step and the crosslinking reaction is carried out after the extrusion step. The conductor element is pre-heated in a pre-heating step before the extrusion step by generating inductively eddy currents inside the conductor element which will heat up the conductor element. The pre-heating step is carried out by increasing temperature of the conductor element gradually so that temperature difference between outermost region of the conductor element and the inner layer of the conductor element remains below a pre-determined level at the end of the pre-heating step.