•Sulphur hexafluoride is investigated as a stripper gas in tandem accelerators.•For heavy ions at low terminal voltage, mean charge states are found to be up to 1 charge unit higher than with argon gas.•Charge state distributions are found to be broader than with argon gas.•For charge states above the mean charge state, yields are typically doubled using SF6.•Using SF6 stripper gas, the efficiency of actinides AMS analysis is doubled. We have investigated sulphur hexafluoride as a stripper gas in tandem accelerators by using the ANTARES accelerator system at ANSTO to measure charge state distributions for this gas. Results are reported at 4MV terminal voltage for injected negative ions ranging from carbon to uranium oxide. For iodine and thorium the distributions are extended across a range of energies of practical use for accelerator mass spectrometry, ion beam analysis and other accelerator applications. Charge state distributions using sulphur hexafluoride are found to have mean charge states up to 1 charge unit higher than, and to be broader than, corresponding distributions for argon gas, except in the case of carbon beams. As a result, SF6 is shown to provide significantly higher yields for charge states of heavy ions above the mean charge state. We now perform actinide AMS measurements with 9% yield to the 5+ charge state, compared to 4–5% achieved previously with argon gas.