The oxidation of methane on PO4-deficient barium hydroxyapatite (BaHAp) has been investigated in the presence and absence of tetrachloromethane (TCM). In the absence of TCM, the principal product was CO2 with less than 20% selectivity to partial oxidation and oxidative-coupling products. On introduction of a small partial pressure of TCM to the feedstream and with higher times-on-stream, the formation of CO2 was virtually eliminated while CO and the C-2 hydrocarbon became the dominant products. The observations with TCM can be attributed to the chlorination of the catalyst and, in particular, the formation of the corresponding chlorapatite.