The arc stability and erosion behaviour of a hollow graphite DC cathode were studied using a graphite anode in an argon atmosphere. The main factors controlling the arc stability were the geometry of the cathode tip and the argon gas flow rate. It is suggested that high argon gas flow rates might shift the electron emission mechanism of the cathode from the thermionic-field to the thermionic emission regime. Arcs were generally stable if the cathode is in the thermionic emission regime. The erosion rate of the cathode at 150 A was strongly dependent on the arc stability and higher for the unstable arc operation. Meanwhile, the erosion rates at 300 and 400 A showed the opposite trend because of carbon redeposition.