Technical rehearsal of tritium operation at JET

•In preparation for the future tritium and deuterium-tritium campaigns at JET, a rehearsal of the procedures and technical systems was performed.•The rehearsal included commissioning and characterisation of the NBI performance with a tritium-like gas feed configuration.•A prototype tritium introduction module was tested and the torus hall depression and oxygen depletion system commissioning was started.•The rehearsal also included emergency exercises, training of personnel, testing and optimising operational procedures.•The rehearsal demonstrated that JET is still capable of operating with tritium in a safe and reliable manner.