Polypyrrole nanostructures with diameters less than or equal to 10 nm have been electropolymerized using step and pit defects on highly ordered pyrolytic graphite (HOPG) as templates for electropolymerization. Step defects were naturally occurring, and pits were formed via oxidation of freshly cleaved surfaces of an HOPG wafer by heating at similar to 640 degrees C. Underpotential deposition of approximately similar to 80 mV caused polypyrrole to form only on the step and pit edges of HOPG at and not on the basal plane. The size of these nanostructures could be controlled by limiting the pyrrole polymerization time at anodic potentials. Recent modeling results allow the morphology of the deposition to be inferred, and we find the electrochemical data consistent with wire-shaped growth for up to 30 s at constant potential, after which the growth changes morphology. Scanning tunneling microscopy data confirm this result. Preliminary studies show that these polypyrrole nanostructures can be removed by sonication.