A first principles treatment of the photodissociation of HCl and DCl from 50000 cm (1) to 75000 cm (1) is presented. The treatment is the first to correctly reproduce the asymmetric absorption pro. le observed for HCl. The theoretical model for the HCl and DCl photodissociation presented in this study considers a dissociation process that occurs on a repulsive electronic state (A(1)Pi) coupled to a bound electronic state (C-1 Pi). The asymmetry in the HCl cross section arises because of the radial coupling introduced by the rotation-free nuclear kinetic energy operator. (C) 2009 Elsevier B.V. All rights reserved.