A method has been proposed to measure self-diffusion in metals by measurement of the contact conductance of an interface between two metallic spheres or hemispheres. By combining Kuczynski's equation for self-diffusion with Bowden and Tabor's equation for the contact conductance between two metallic spheres a relationship has been obtained between contact conductance and the time of heating of the spheres. Thus by measurement of junction conductance as a function of time of heating, for different temperatures, diffusion coefficients and the heat of self-diffusion can be evaluated in the normal manner. A similar relationship has been obtained for two spheres or hemispheres initially pressed together to give a known contact conductance before heating.