Zeolite-beta and mordenite were impregnated with 0.1 wt.% Pt and varying (0,0.1, 0.3, 0.5 wt.%) amount of Ni. The line broadening XRD analysis indicates that the increasing Ni addition decreases the crystallinity of zeolites. The TEM analysis indicates that the average metal particle size increases with increasing Ni addition. The states of Ni and Pt were analyzed by ESCA. The acidity measurements by both TPD of ammonia and pyridine adsorbed FT-IR spectroscopy show the occupation of some of the acid sites by the added Ni species. Ni addition up to 0.3 wt.% over 0.1 wt.% Pt/H-beta and 0.1 wt.% over 0.1 wt.% Pt/H-MOR enhances the ethylbenzene conversion, isomerization selectivity and sustainability of the catalysts. Further Ni addition above the threshold value leads to a drastic drop in activity and isomerization selectivity. Zeolite-beta-based Ni-Pt catalysts always show higher activity and selectivity than mordenite-based catalysts. (c) 2006 Elsevier B.V. All rights reserved.