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 (in cm(2)/s) are as follows : chalcocite, (D) over tilde = 38.7 exp(-5600/T); chalcopyrite, (D) over tilde = 15.4 exp(-6000/T) and bornite, (D) over tilde = 14.5 exp(-4900/T). The component diffusion coefficients (D) are obtained by using the thermodynamic factor, this being 4250, 6500 and 1500, respectively. The diffusion coefficients obtained are in reasonable agreement with literature data, even for chalcopyrite and bornite, with Values previously acquired with a tracer technique at much higher temperatures.