Electrochemical techniques such as chronopotentiometry and a.c. impedance spectroscopy have been used successfully to characterise the behavior of sputter-deposited platinum on highly oriented pyrolytic graphite (HOPG) substrate under hydrogen evolution reaction (HER) in 1 M NaOH at 25 degrees C. Prior to the sputtering process, HOPG surfaces were etched up to 60 min and deposition time was varied up to 20 min. Under a constant applied current density, the rate of overpotential increase with time and its magnitude are strongly related to the experimental conditions during the electrode preparation. Deactivation during HER is attributed to a loss of sputtered platinum due to its poor adhesion to the substrate.