Catalytic properties in the reaction of oxidative coupling of methane (OCM) of HF-modified fly ash ferrospheres separated from combustion brown coal are investigated. It is established that the modification of ferrospheres results in a significant increase in the efficiency of C₂-hydrocarbons formation at 750 °C, the yield increases by 1.5-2.0 times, the content of ethylene in the C₂-products - up to 30 %, and at 850 °C - up to 65%. It is suggested that the high efficiency of ethylene formation is associated with the formation of oxifluoride centers, which are deactivated at 850 °C and converted into oxide centers of deep oxidation.