The hydrogen evolution reaction (HER) was studied on Ni-P electrodes containing 8 to 30 atomic percent P prepared by galvanostatic deposition. The electrodes were studied directly after preparation or after retreatment by heating, leaching in HF solution, anodic oxidation; or potential cycling in the solution. The activity of these electrodes depended on the method of preparation and phosphorous content. The activity was higher for the materials deposited at lower temperatures and for those containing smaller amounts of phosphorous. The mechanism of the hydrogen evolution reaction was studied in 1 M NaOH, and the kinetic parameters were determined using steady-state polarization and electrochemical impedance spectroscopy techniques.