Nanoscale Pt structures were prepared on highly ordered pyrolytic graphite (HOPG) by chemical vapor deposition. The organometallic compound Pt(COD)(CH3)(2) (1) (COD is 1,5-cyclooctadiene) was reduced by hydrogen gas to effect the deposition of Pt. The deposited Pt was characterized by cyclic voltammetry and by tapping mode scanning force microscopy. Tt was found that Pt initially nucleates at, defect sites on HOPG. These nucleated sites then catalyze the hydrogenation of 1 to further deposit Pt adatoms. At low coverages, we observe substrate defect decoration by "nanobead" type structures. Structures that emanate from defect sites onto the basal plane form at higher coverages.