The study of corona discharge is important for successful development of various electrostatic technologies. The current study is directed at investigating the stability of a negative polarity direct current corona discharge in high pressure nitrogen. Experiments were carried out at test set-up equipped with a high temperature high pressure (HTHP) corona discharge ionizer which has star-shaped disk high voltage electrodes installed inside of a cylinder grounded electrode. The “direct” and “indirect” current–voltage characteristics (CVCs) were measured for various gas pressure values without and with a gas flow through the HTHP set-up casing and without external heating of the ionizer grounded electrode. An increase of gas pressure results in an increase of a “CVC-direct” onset voltage and in a decrease of the corona current at a constant value of the applied voltage. A hysteresis effect is observed for the corona discharge CVCs at a high gas pressure when corona currents for the “CVC-indirect” are measured at voltages lower than the “CVC-direct” onset voltage. The area of the “hysteresis window” increases with an increase of gas pressure.