Breakdown of the ions created by photoionisation of C 6 F 6 at 73.6, 58.4 and 30.4 nm has been examined by two separate photoelectron-photoion coincidence techniques and has been interpreted using density functional theory calculations. A full breakdown diagram, amplifying earlier metastable ion studies, is determined. The rate of the main dissociative rearrangement reaction forming C 5 F 3 + , measured as a function of the internal energy of the ion, has been fitted by RRKM calculations and a large kinetic shift is found. The structure of the C 5 F 3 + ion and its 0 K threshold have been obtained from the experiments and also from theoretical calculations. Calculations of all the vibrational frequencies of the ground state hexafluorobenzene cation agree with existing experimental data.