Diffusion measurements have been performed by an electrochemical potentiometric method on polycrystalline synthetic chalcocite (Cu2S), chalcopyrite (CuFeS2) and bornite (Cu5FeS4) in the temperature range 5-50 degrees C. The chemical ((D) over tilde) diffusion coefficients are as follows: chalcocite 38.7 exp(-5600/T); chalcopyrite 15.4 exp(-6000/T) and bornite 14.5 exp(-4900/T).