Spectroscopy and dissociation of HCl2+, HBr2+ and HI2+ have been studied in detail using ab initio MP2, CCSD and CCSD( T) and the density functional B3LYP methods. In the dissociation processes, the fragmented atoms have been considered to be either in their ground or in their valence excited states. The spectroscopic constants of these dications have been calculated using the ab initio and the density functional methods. Most of the spectroscopic constants are first reported and the rest agree well with existing theoretical and experimental data. Interesting results have been obtained for the dissociations of these dications. (C) 2008 Elsevier B.V. All rights reserved.