Improvements in the aromatization of hydrocarbons and in the alkylation of aromatic rings effected by contacting appropriate hydrocarbon feed streams with a ZSM-5 type of catalyst at prescribed temperature, pressure and space velocity conditions to convert the feed as required and desired, which improvements go to minimizing the production of polycyclic aromatics, particularly naphthalenes in the process and reducing coking of the catalyst during aromatization and/or alkylation by using as the catalyst a ZSM-5 type of crystalline aluminosilicate zeolite which has rhenium values deposited thereon and therein by ion exchange techniques.