The cathodic polarization behavior of , , , , and at room temperature has been determined in 1M perchlorate solutions at pH 0.04 and pH 10.8 up to −1.0v vs. the reversible hydrogen electrode. Measurements were also made on Ni, Si, Sb, Te, and on Ni electrodes exposed to and . , Te, Si, and exhibit kinetic peculiarities which are probably attributable to hydride formation, but these features are not generally shown by the corresponding nickel compounds. With the exception of Si in acid solution, all of the electrodes show an extended Tafel line indicating the hydrogen evolution reaction with the following characteristics. In alkaline solution, the Tafel slope is greater than 100 mv for all metals, while the exchange current is between 10−5 and 10−8 amp/cm2. In acid solution, Ni, Sb, , , and have slopes close to 120 mv, while Te, , , and show slopes between 50 and 80 mv. The exchange currents in acid solution vary from about 10−5 for Ni to about 10−11 amp/cm2 for Te. For , , and , there exist regions where the current densities at a given overpotential exceed those on either of the individual elements. Results are discussed with a view to distinguishing the role of atomic and crystal factors in the electrocatalytic activity of the electrode materials. The intrinsic chemical properties of the surface atoms appear to dominate the mechanism of the hydrogen reaction, while the crystalline properties strongly influence the rates.