Abstract: To study the influence of atomic oxygen on the LaB₆ hallow cathode, the LHC-5 hollow cathode is placed in the atomic oxygen test facility with repeated ignitions, and with the tungsten-rhenium 5-26 thermocouple to measure the temperature of the cathode tube. After the test, the hollow cathode is inspected, and the cathode tube appears to be expanded and cracked. The XPS analysis of the cross section shows that the failure of the cathode tube is caused by oxidation. Therefore, protective measures should be taken for LHC-5-type hollow cathode ion thrusters, the Hall thrusters and the plasma contactors in LEO under atomic oxygen attack, and a correct shutdown strategy is essential for ensuring the normal work of the cathode.