Results of Diamond and Wert on the kinetics of the reorientation of carbon pairs in nickel are used to demonstrate that the low activation energy reported by Massaro and Petersen for diffusion of carbon in nickel at 350–‐700°C cannot be explained by a change in the mechanism for the lattice migration of carbon. Boundary diffusion also appears incapable of explaining the results, and it is concluded that there may be unsuspected difficulties with the particular method of measurement employed for the diffusion measurements.