A catalyst system that exhibits a ratio of ethylene saturation to aromatics ring saturation of greater than 3,500. The catalyst system comprises two components and each component comprises a crystalline molecular sieve having a Constraint Index of from about 1 to about 12 and an effective amount of Group VIII metal. The catalyst system finds particular application in ethylbenzene conversion/xylenes isomerization reactions. The catalyst system can be prepared by incorporating the Group VIII metal into the molecular sieves by competitive ion exchange.