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The electrochemical deposition and reoxidation of Au on the basal plane of highly oriented pyrolytic graphite (HOPG) immersed in a 5 mM AuCl4^-/6 M LiCl solution is reported. Scanning electron microscopy (SEM) and ex-situ atomic force microscopy (AFM) demonstrate that Au nanoparticles, ~3.3 nm in height and ~10 nm in diameter, are deposited at times less than ~1 s. The density of nanoparticles, 6 × 10⁹ cm^-2, is of the same order of magnitude as the surface point defect density, suggesting that point defects act as nucleation sites for Au electrodeposition. A small subset of the Au nanoparticles (~7%) continues to grow between 1 and 50 s, reaching a height of ~150 nm and a diameter of ~300 nm. At times greater than 50 s, the larger particles coalesce to yield a surface comprised of a low density (~2 × 10⁶ cm^-2) of micrometer-size Au crystallites surrounded by Au nanoparticles. Double potential step chronocoulometric experiments demonstrate that the electrodeposition of Au is chemically irreversible, a finding supported by SEM and AFM observations of Au nanoparticles and larger crystallites on the surface after long periods of reoxidation (>3600 s). Au nanoparticles are observed to be preferentially deposited on the upper plane of step edges, a consequence of the nonuniform surface electron density that results from relaxation of the graphite lattice near steps.