Thermally stable strontium hydroxyapatite (SrHAp) was prepared with a variety of stoichiometries and employed as catalysts for the oxidation of methane with oxygen and nitrous oxide in the presence and absence of tetrachloromethane (TCM) as a gas-phase additive. In contrast to the oxidation of methane on thermally unstable SrHAp, non-selective oxidation to CO and CO2 at 873 K proceeded with oxygen while the selectivity to CO increased with increasing time-on-stream in the presence of TCM and was higher than 90% at 6 h on-stream, regardless of the Sr/P ratios in the catalysts. However, with nitrous oxide the selectivity to CO in the presence of TCM was strongly influenced by the Sr/P ratio with smaller values producing higher CO selectivity. In the presence of TCM, the catalyst consists of a complex mixture of the hydroxyapatite, the corresponding chlorapatite, phosphate, chloride and oxychloride, each of which contributes dissimilarly to the catalytic process.