This study dealt with evaluating the (J85-GE-5H) military turbojet engine (TJE) in terms of exergetic and advanced exergetic analyses at Military (MIL) and Afterburner (AB) process modes by utilizing kerosene (JP-8) and hydrogen (H2) fuels. First, exergy and advanced exergy analyses of the engine were performed using JP-8 fuel as per actual engine operating conditions. These analyses of the turbojet engine using hydrogen fuel were also examined parametrically. The performance evaluation of the engine was lastly executed by comparing the obtained results for both fuels. Based on the parametric studies undertaken, the entire engine’s exergetic efficiency with JP-8 was reckoned 30.85% at the MIL process mode while it was calculated as 16.98% at the AB process mode. With the usage of H2, the efficiencies of the engine decreased to 28.62% and 15.33% for the above mentioned two modes, respectively. As the supreme exergy destructions occurred in the combustion chamber (CC) and afterburner exhaust duct (ABED) segments, the new technological developments should be considered to design more efficient engines. As a result, the engine worked less efficiently with hydrogen fuel due to the enhancement in exergy destructions. Conversely, the greenhouse gas (GHG) emission parameters lessened with the utilization of H2 fuel.