Benzene, toluene and xylene are prepared from mixtures of single ring alkyl aromatic compounds of eight or more carbon atoms concurrently with isomerization of xylenes by mixing xylenes from which at least one isomer has been separated with a mixture of alkyl benzenes of eight and more carbon atoms, e.g. heavy reformate, and contacting that mixture at 800.degree. to 1000.degree. F. with a zeolite catalyst of reduced activity such as zeolite ZSM-5 having a silica to alumina ratio of at least 200.