Mesoporous ultra-stable Y zeolite with outstanding performance for heavy oil cracking was prepared through the combination of desilication and dealumination. Atomic removal of silicon atoms from the starting NaY zeolite framework during desilication was reported. Nucleation and propagation of mesopores in the following dealumination process was studied. Si(0Al) and Si(1Al) atoms are selectively removed from zeolite framework by desilication. Consequently, silanol nests and unique hydroxyl nests with framework associated Al-OH were created in the framework of the desilicated zeolite. The artificial defects effect the initiation of mesopores in crystal parts where used to be rich in framework silicon and unfavorable for mesopore formation and promote the propagation and coalescence of mesopores. Catalytic studies revealed improved activity and lifetime in the crack of 1,3,5-triisopropylbenzene and showed increased gasoline and light cycle oil selectivity when the conversion of a heavy oil was compared. (C) 2012 Elsevier Inc. All rights reserved.