The double photoionisation spectrum of molecular iodine has been measured at three wavelengths by the TOF-PEPECO technique and is interpreted using relativistic molecular structure COSCI calculations of potential curves for a large number of electronic states connected to the three lowest groups of dissociation limits. The lowest double ionisation energy is 24.85 ± 0.02 eV (adiabatic) or 24.95 ± 0.02 eV (vertical). It is associated with the electronic state of . The double ionisation process is mainly direct, and positions and widths of the bands are well reproduced by the calculations.