Recent developments in noble gas chemistry have illustrated the potential for noble gases such as argon and krypton to participate in chemical bonding. In this study, electron correlation methods (i.e. CCSD(T)) in combination with the correlation consistent basis sets [cc-pVxZ, aug-cc-pVxZ, cc-pV(x + d)Z, and aug-cc-pV(x + d)Z, where x = D(2), T(3), Q(4), 5] have been used to investigate the ground and transition state structures, vibrational properties, and relative energetics of the recently observed HKrCl species. The decomposition pathway of HKrCl to HCl + Kr has also been examined. (C) 2004 Elsevier B.V. All rights reserved.