A spot welding rod for resistance welding of object comprises a rod which is moveable axially, and two electrode arms provided with electrodes, wherein the electrodes face towards each other and the welding gun is adapted to press together objects to be welded located between the electrodes by axial movement of the rod, and to allow welding current to flow between the electrodes. The rod axis extends in a direction which is generally perpendicular to the directions of the electrodes and at least one of the electrode arms is pivotally mounted. The welding gun includes structural elements which are connected operatively to the at least one pivotally mounted electrode arm and the rod. The structural elements are disposed between the point at which the one of the electrode arms is pivotally mounted and the electrodes and mutually engage one another and move translatively relative to each other and therewith force at least one of the electrodes towards the other electrode through the medium of a wedging action as the rod is moved axially.