Dr Y LiALI AHMED MUFFAREH HARTHI2022-05-262022-05-26https://drepo.sdl.edu.sa/handle/20.500.14154/34580the research focuses on how hydrogen effect on the engine performance. Siemens SGT-800 model was created using PYTHIA version 5.1 software and its validation was done depending on the information relating to performance in the catalogue of Siemens. The design and off-design analysis of performance was done with natural gas and hydrogen, to help comprehend the way in which they impact on the performance at varying mixing ratio , part load and also at different ambient temperatures and altitudesen