The influence of the composition of new materials-mesoporous amorphous lanthanide silicates-on the features of their porous structure and the effectiveness of the oxidative coupling of methane (single-stage production of ethylene, ethane, and their homologues from methane) is revealed. The synergistic effect in this reaction of La and Ce ions introduced into the silicate matrix at the sol-gel synthesis stage, which results in an nonadditive growth in the yield of coupling products from 5-7 to 14-18% in the presence of both ions in the composition of the contact catalyst, has been shown.