The kinetics of the underpotential deposition (upd) of H and the hydrogen evolution reaction (her) have been found to be extremely sensitive to the surface geometry of Pr single-crystal surfaces. The order of electrocatalytic activity at the low-index planes was found in our previous studies to be (100) < (111) < (110). The study of the kinetics of the her at Pt(hkl) electrodes in 0.5 M H2SO4 is found to be complicated by the influence of H-2 diffusion away from the surface. However, increase of the pH decreases the kinetic facility of the hydrogen electrode reaction, i.e. abstraction of H to form H-2 is more difficult from H2O than from H3O+; at such lower rates, diffusive effects can be totally eliminated by electrode rotation. In the present paper we show that in 0.5 M NaOH the order of reactivity is identical with that found in acidic media, viz. (100) < (111) < (110). The slower rates arising in alkaline: media allow a larger potential range to be: probed and, unlike the situation in acid, quantitative rate information for each of the Volmer, Heyrovsky and Tafel steps of the her was obtained by using electrochemical impedance spectroscopy (EIS) and steady-state de methods. As well as rate information, the charge, q(1), corresponding to maximum fractional coverage by the overpotentially deposited H species (opd H), can be obtained and will be discussed in terms of the results previously found in acid, related to surface geometry and coverage by upd H. The results of the present work will also be compared with those of other recent studies conducted in alkaline media.