More/all-electric aircraft is one of the most promising development directions for aircraft. However, the performance of the turbine engine will be strongly affected by the high electric power fraction when the electric power is extracted from the main engine. In order to improve aero-engine performance and electric power fraction, the turbojet engine integrated with an interstage turbine burner (ITB) and solid oxide fuel cell (ITB-SOFC engine) is proposed in this paper. Turbojet engine provides thrust for propulsion and SOFC provides electric power for electrical equipment. In order to evaluate the performance of the ITB-SOFC engine, the thermodynamic analysis model of the engine performance is developed. Analysis results show that the ITB-SOFC engine has advantages in thermal efficiency and specific thrust over the turbojet engine, the increments of these two parameters can reach 2.94% and 23.87% respectively. There is a limitation in pressure ratio for the ITB-SOFC engine, which is 24. The electric power fraction of the ITB-SOFC engine can vary in a wide range. The specific thrust increment over a turbojet engine is high up to 24.07% if the electric power fraction is high up to 0.2. (C) 2018 Elsevier Ltd. All rights reserved.