The interaction of highly oriented pyrolytic graphite with nitric acid in a wide range of its concentrations was studied by potentiometry and X-ray. The threshold values of HNO3concentration for the different stages of graphite nitrate formation have been determined during spontaneous and electrochemical intercalation. At anodic oxidation of graphite in 55–98% HNO3the typical step-like character of the dependence of potential E(Q) is observed. The polarization of graphite (I=100μA) in 55–98% HNO3results in obtaining the 2nd stage graphite nitrate. The increase of a current intensity (I) up to 1.5 mA allows to carry out synthesis of the 1st stage in 75–98% HNO3.