A method has been devised whereby fractions of a monolayer of adsorbed H, corresponding to the steady state concentration of H upon Ag electrodes during the evolution upon them of electrolytic H 2, may be measured to an accuracy of about 25%. It utilizes galvanostatic charging techniques to obtain the total quantities of electricity utilized in dissolving H anodically from the electrode under conditions when oxide is also formed upon it, and a further galvanostatic charging process by which a correction for the oxide formation can be made. Rigorous experimental conditions must be employed. Special techniques have been employed in preparing the surface of Ag electrodes in a reproducible state, in preparing the solution in a state relatively free from depolarizers, and in changing the mode of polarization of the electrode from constant cathodic current to constant anodic current in 2 μsec. The results are strongly dependent upon the current density of the anodic charging process, and reach a constant low value when this is sufficiently high. At an over-potential of −400 mV on Ag in o.r N NaOH, about 10% of the electrode surface is covered with H. The degree of coverage varies logarithmically with the current density of cathodic polarization. The presence of 10 −4 moles/l As 2O 3 in the solution increases the steady state concentration of H by about 250%. The potential at which H dissolution commences, and the variation of the steady state coverage of the electrode, are consistent only with a rate-determining discharge of protons from water molecules, followed by a recombinative desorption. “Reduced rate constants” for the discharge and combinative desorption are calculated.