Oxidation at the oxide/Si(111) interface at room temperature (RT) and 550 °C has been investigated by real-time X-ray photoelectron spectroscopy. Self-accelerating interface oxidation is observed in oxidation at RT, but not in oxidation at 550 °C. During self-acceleration at RT, the component corresponding to strained Si atoms in the second layer below the oxide/Si(111) interface, Siβ, increases significantly. It is suggested that the interface oxidation rate is strongly correlated with the generation of strain at the oxide/Si(111) interface. Furthermore, a self-accelerating interface oxidation model of Si(111)7 × 7 surfaces that includes the point defect (emitted Si atoms + vacancies) generation is proposed. Copyright © 2014 John Wiley & Sons, Ltd.