Diffusion measurements on three copper-containing sulphides have been performed by an electrochemical potentiometric method. -- The diffusion coefficient for chalcocite is in good agreement with values found previously, and a reasonable agreement is also found for chalcopyrite and bornite when our data are compared with values acquired at much higher temperatures with a different technique. The activation energies are remarkably similar for the three sulphides, considering that their relative errors are of a 10% magnitude, which indicates that the bonding strengths and the diffusion mechanisms are similar.