The effect of the pH of the growth solution on the size and crystallographic orientation of gold nanoparticles (GNPs) was studied during the course of the preparation of surface-confined spherical GNPs following a two-step protocol (electrochemical and chemical). GNPs were first electrodeposited onto a clean glassy carbon (GC) electrode and these GNPs were used as seeds. Seed-mediated growth of the electrodeposited GNPs was performed in a solution of H[AuCl4] at various pHs (5.0 to 0,5) using NH2OH as a reducing agent. The thus-prepared GNPs were characterized by electrochemical, UV-visible absorption spectral, SEM, and TEM studies. The nucleation (i.e., formation of the new seeds) was found to dominate over growth (Le., enlargement of the seed particles) process at higher pH during NH2OH seeding, whereas only growth was recognized at low pH (0.5). Nonspherical byproducts were noticed when the seed-mediated growth was performed at higher pHs, but at pH 0.5 only spherical GNPs were observed. The present method provides a way out for the preparation of GNPs with homogeneous shape resolving the problem of simultaneous formation of nonspherical byproducts during the seed-mediated growth as well as for the preparation of GNPs with a Au(111) facet ratio as high as 97%. On the basis of the obtained results, the mechanism of the growth process at low pH is also discussed. Interestingly, an enhanced electrochemical response was obtained for the oxidation of H2O2 using the GNPs prepared at pH 0.5.