Abstract: The present invention provides a process for cracking or decomposing a feedstream containing a major proportion of at least one dialkyl ether to produce the corresponding olefins comprising contacting the feedstream with a faujasite aluminosilicate catalyst which is characterized in that at least about 50 wt. % of the alkali metal content originally present in said faujasite has been exchanged by at least one alkaline earth metal. The decomposition is preferably conducted in the vapor phase at preferred temperatures in the range of from about 125.degree. F. to about 600.degree. F. The process offers the advantages of longer catalyst life coupled with high yield and selectivity rates towards olefin production.