Stability in ambient air or in vacuum‐controlled atmosphere of molecular oxygen‐induced p‐type doping of graphene monolayer on SiO2 substrate on Si is investigated by micro‐Raman spectroscopy and atomic force microscopy (AFM). The Raman 2D and G bands spectral positions and amplitude ratio are affected by the permanence in air atmosphere in a time scale of months whereas the vacuum safely maintains the doping effects determined through Raman bands. No morphological effects are induced by the doping and post‐doping treatments. A reactivity of ambient molecular gas with stably trapped oxygen is suggested to induce the doping modification.