Processes for preparation of an epitaxial graphene surface to make it suitable for deposition of high-κ oxide-based dielectric compounds such as Al2O3, HfO2, TaO5, or TiO2 are provided. A first process combines ex situ wet chemistry conditioning of an epitaxially grown graphene sample with an in situ pulsing sequence in the ALD reactor. A second process combines ex situ dry chemistry conditioning of the epitaxially grown graphene sample with the in situ pulsing sequence.