All-electron and effective core potential (ECP) calculations have been performed on boron dibromide and its cation. These calculations have allowed the determination of a reliable ECP method, which was subsequently used to perform calculations on boron diiodide and its cation. Density functional calculations were then performed using ECPs : this combined approach was found to be an inexpensive way of obtaining reliable results. The results of these methods were then used to calculate ionization energies of these species. The adiabatic ionization energy of each species is calculated to be 6.95 eV (BBr2) and 6.61 eV (BI2) using ECP methods. For BBr2 the adiabatic energy was also calculated using ail-electron methods, which showed that the ECP methods were reliable. The expected appearance of the photoelectron spectra of these species is briefly discussed.