Thermally stimulated desorption and x‐ray photoelectron spectroscopy were used to study the air oxidation at room temperature of HF‐treated Si(100) surfaces. The desorption results indicated an appreciable density of hydrogen at the surface. Air oxidation experiments with predesorbing surface hydrogen were carried out and an obtained linear relationship between the amount of H2desorption and oxidation indicated that the oxidation was allowed by H2desorption. The surface hydrogen was also found to be stable in air at room temperature and to contribute to a retardation in air oxidation of the surface.