Abstract: Process and kit for passivating in situ a tip of a probe for an active implantable medical device, particularly for a cardiac pacemaker probe. The probe (10) is of the type comprising a hollow insulating sheath (12) made of a supple material having an internal conductor (14) terminated at its distal extremity by an electrode (16), an axial canal (18) along its length, and a support element (22) at its distal extremity in the neighborhood of the electrode, particularly a metallic filament or blade for shaping or reinforcing the distal extremity (20) of the probe. The support element is of a rigidity that is greater than the combination of the sheath and the internal conductor.