A process to prepare propylene showing desirably increased selectivity comprises contacting, at an elevated temperature, ethanol and a rhenium oxide-modified ZSM-5 zeolite catalyst, under conditions suitable to form propylene. The rhenium oxide-modified ZSM-5 zeolite catalyst may be prepared by impregnating, in an aqueous or organic medium, a ZSM-5 zeolite with a rhenium source, under conditions suitable to form a catalyst precursor, and calcining the catalyst precursor under conditions suitable to form a rhenium oxide-modified ZSM-5 zeolite catalyst.