The exchange of silver ions between the (111), (100), (110), and (311) surfaces of single‐crystal silver and silyer nitrate solutions has been studied, using Ag110 as tracer. The initial step is very rapid and is probably largely adsorption, since much of the radioactivity acquired during the first few seconds can be removed by soaking in distilled water. After about 15 min the rate‐controlling process appears to be diffusion in the solid. In solution the radioactivity uptake continues steadily if the surfaces are frequently desorbed with distilled water, but if the adsorbed ions are allowed to remain, the rate of uptake is reduced. In solution the radioactivity on the surfaces reaches constant values after 4 days, whether or not desorption is carried out. The penetration profile and diffusion coefficient in the metal were obtained by “chemical sectioning.” It was found that diffusion occurred by means of “dislocation pipes,” and resembled grain boundary diffusion rather than lattice diffusion by a vacancy mechanism which occurs at high temperatures.