With the global need for atmospheric decarbonization, the use of alternative fuels in the aviation sector has become significant in recent years. Hydrogen is a form of renewable energy that can be produced cleanly and is a promising alternative to fossil fuels, contributing to the reduction of greenhouse gas emissions and the transition to a cleaner and more sustainable aviation sector. The aim of this study is to perform comparative thermodynamic modeling on a General Electric GE-90 Turbofan engine using both aviation kerosene and hydrogen in three flight stages: Climb, Cruise, and Approach, examining the advantages and disadvantages of each fuel in this type of engine. This analysis was carried out using two software programs: Matlab and Gasturb, to facilitate a better comparison between the results. Moreover, calculations were made of the emissions generated by this engine on a Rio de Janeiro – Paris flight in a Boeing 777- 300ER, including the three flight stages, using both hydrogen and aviation kerosene. For kerosene, emissions of 𝐶𝑂2, 𝐶𝑂, 𝐻𝐶, 𝑀𝑃, 𝑁𝑂𝑥 𝑒 𝐻2𝑂 were calculated, while for hydrogen, only 𝑁𝑂𝑥 and 𝐻2𝑂 were considered. As a result, the simulation outcomes were then compared for the two fuels, where it was observed that to produce the necessary thrust for the three defined flight stages, hydrogen required a flow rate approximately 3 times lower than kerosene, maintaining the aircraft s performance. In contrast, there was an increase in the combustion chamber exit temperature, which in turn led to an increase in 𝑁𝑂𝑥 emissions during the climb and approach phases, while in cruise flight there was a reduction in these emissions, mainly due to the fact that the flow rate difference had a greater influence on the calculation. However, adding up these factors, the use of hydrogen reduced this pollutant by about 60%. Furthermore, as the combustion process of hydrogen mainly produces water, there was a significant increase in the emission of 𝐻2𝑂 vapor, equivalent to 3 times more compared to kerosene, which can lead to contrails and cloud formation, potentially affecting climate change.