AbstractHNO3and HClO4were intercalated into the graphite lattice by means of chemical oxidants and by electrochemical oxidation. In both cases the potential variation versus time was recorded in order to trace the intercalation process. Compared with H2SO4, the intercalation reactions of nitric and perchloric acid proved to be fast. Impedance measurements indicated that the penetration of the phase boundary by acid anions, acid molecules and water as well as intercalate nucleation determine the reaction rate of the chemical insertion reactions. Biintercalation and cointercalation compounds with HNO3and HClO4were prepared for the first time.