The objective of this work is to investigate interface chemistries which minimize the interfacial silicon oxide transition region at Si/high-k dielectric interfaces. We report on the mechanism by which a silicon native oxide layer is converted into magnesium silicate. The deposition of metal Mg onto a SiO native oxide surface resulted in the formation of a magnesium silicide in addition to substochiometric silicon oxides and a significant decrease in the oxidised silicon signal. Annealing to 300 °C resulted in the decomposition of the magnesium silicide, oxidation of the Mg, and the desorption of excess metallic Mg. Subsequent annealing to 500 °C resulted in converting the SiO2 into magnesium silicate. The results suggest that the decomposition of the Mg silicide in the presence of the residual native oxide facilitates silicate formation at 500 °C. Due to the reported thermal stability of Mg silicate it is suggested that this process may be beneficial in modifying the interface characteristics of the Si/high-k dielectric interface which has potentially significant implications for future semiconductor device generations.