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.