Strontium Zirconium phosphate, unpromoted strontium chlorapatite and strontium hydroxyapatite showed low C₂ selectivity for the oxidative coupling of methane, but promoted strontium chlorapatite catalysts showed markedly increased activity and selectivity and also exhibited stable behavior. SrCl₂ was the primary promoter and strontium zirconium oxides were considered to be acting as other promoters, but strontium zirconium phosphate and strontium carbonate seemed to be acting adversely. Apromoted strontium chlorapatite catalyst which contained a slightly larger amount of SrCl₂ than needed to form the chlorapatite showed the best perfomance and was stable up to 50 h at 1,023 K, and the highest C₂₊ selectivity and yield were 52% and 13.8%, respectively. Although SrCl₂ was more stable than NaCl it decomposed slowly during the reaction, leaving strontium oxide or strontium carbonate behind, which is considered to result in slow deactivation of the catalyst.