From Rehbiner effects measured during creep tests on pure nickel wires in electrolyte solutions, it is concluded that, under conditions where there is no oxide or hydroxide, there is still an adsorbed species present on the "clean" metal surface. This species, probably (NiOH)ads, is formed by strong Ni-water interactions and can be removed by electrochemical reduction at low potentials or by lowering the solution pH.From creep tests on thin gold wires in various electrolyte solutions, it has been concluded that dislocations emerging at the surface of a loaded specimen can be pinned by certain chemisorbed ions or by adsorbed oxygen containing species, including OH -ions and water molecules (1-3).Reference (1) describes the characteristic features of the strain responses of stressed gold wires to cathodic potential pulses, and a definition is given of the concept of "extra strain." Strong dislocation pinning due to hydroxyl ions occurs in alkaline solutions. As a result of this pinning effect by adsorbed OH -ions, an extra strain is observed when a gold wire specimen, loaded at a potential above the pzc in an alkaline solution, is subjected to cathodic polarization below the pzc. A confirmation of the role of OHions in pinning surface dislocations is found in the fact that a change in the solution pH, by adding acid, causes a similar extra strain effect.Dislocation pinning by adsorbed water molecules is demonstrated in the case of gold by the extra strain effects measured when the potential is lowered into the range where the water reduction reaction can occur at an appreciable rate, which is below -1000 mV vs. SCE.Unpublished work in this laboratory has shown that for silver the effects of changes in the potential on the creep rate are very similar to those observed for gold. In contrast, attempts to find Rehbinder effects using pure iron wire specimens yielded only negative results. An experimental difficulty in the case of iron was the irregular creep behavior observed for the thin wire specimens of this metal. Frequent discontinuities in the creep rate made it difficult to distinguish any possible extra strain effects due to potential changes. Effects of cathodic polarization on the creep behavior of copper have been reported in the literature (4). In the present study, it was found that the strain effects of loaded nickel specimen wires following cathodic polarization again showed characteristic features similar to those observed in the case of gold (1). The observed similarities in the creep responses to potential pulses suggests that for the fcc metals Au, Ag, Cu, and Ni the underlying mechanisms will be essentially the same. This means that surface dislocation pinning by adsorbed species on the metal surface will significantly affect the plastic deformation behavior of the surface layers of loaded specimens. In bcc crystals the Peierls Nabarro forces opposing dislocation movement in a glide plane are known to be much larger than in the fcc structure. It is therefore possible that for bcc metals, like iron, ...