Physical properties of surfaces are extremely important for initiation and nucleation of crystal growth, including nanowires. In recent years, fluctuations in surface characteristics have often been related to unreproducible growth of GaAs nanowires on Si by the Ga-assisted method. We report on a systematic study of the occurrence of GaAs nanowire growth on silicon by the Ga-assisted method for different kinds of silicon oxides: native, thermal and hydrogen silsesquioxane (HSQ). We find that success in achieving nanowires and the growth conditions such as gallium rate and substrate temperature depend mainly on the physical properties of the surface: oxide stoichiometry, oxide thickness and surface roughness. These results constitute a step further towards the integration of GaAs technology on the Si platform. (C) 2014 Elsevier B.V. All rights reserved.