The aim of the present work was to carry out a theoretical study on the stability of the different submonolayers of lead adsorbed on the (100) monocrystalline surface of gold observed during the growth of the first monolayer of lead. The calculations were performed using the atom superposition and electron delocalization molecular orbital methodology in the cluster approximation, considering separately the interactions adsorbate/substrate and adsorbate/adsorbate. The present model provided the corresponding structures of minimum energy with respect to the symmetry group detected from low energy electron diffraction measurements reported in the literature. Finally, theoretical results about the stability of the different submonolayers adsorbed are compared with experimental data.