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[Display omitted] • Novel catalysts of SrO x supported on {2 2 2} facets of pyrochlore LZO were synthesized. • Substitution of La3+ cations by atomical dispersed SrO x increase surface oxygen vacancies. • Surface alkaline sites are beneficial to enhance catalytic performance for OCM reaction. • SrO x /LZO-12 catalyst showed excellent catalytic performance for low-temperature OCM. • Surface alkaline center promotes critical steps of C H bond breaking and C C bond coupling. The efficient catalysts of strontium oxide (SrO x) supported on exposed {2 2 2} facets of pyrochlore La 2 Zr 2 O 7 nanocrystals (SrO x /LZO-Y) were elaborately synthesized by incipient wetness impregnation method. The introduction of atomically dispersed SrO x species on La 2 Zr 2 O 7 surface can increase the amount of surface oxygen vacancies induced by Sr2+ substitution of La3+ cations, and the increasing of moderate surface alkaline sites are beneficial to enhance catalytic performance for oxidative coupling of methane (OCM). The SrO x /LZO-Y catalysts have super catalytic performance during low-temperature OCM reaction. SrO x /LZO-12 catalyst with the highest concentrations of O 2 – species exhibits the highest activity and the lowest apparent activation energy (84 kJ mol−1) during low-temperature OCM into C 2 H 4 and C 2 H 6 (C 2) products, i.e., its CH 4 conversion, selectivity and yield of C 2 products at 600 °C are 30.5 %, 47.4 % and 14.5 %, respectively, and its ratio of C 2 H 4 /C 2 H 6 products is 0.77. Based on the results of multiple experimental characterizations, the mechanism of SrO x /LZO-Y catalysts for OCM reaction is proposed: the surface alkaline active centers (O 2 –) induced by doping of Sr ions can promote the critical step of CH 4 activation significantly during low-temperature OCM reaction. It is a new strategy to develop the low-temperature and high-activity catalysts for OCM in practical application. [ABSTRACT FROM AUTHOR]