The catalytic properties of zeolite catalysts modified with rhodium compounds in the synthesis of olefins from dimethyl ether (DME) and methanol (MeOH) have been studied. The optimum concentration of rhodium in the composition of a zeolite catalyst has been determined. It has been shown that one of the possible precursors of ethylene in the conversion of DME is ethanol, which, under reaction conditions, can be formed through both the DME isomerization and methanol homologation stages.