Abstract Using mixtures of hydrogen and natural gas as primary energy sources in current power generation systems with gas turbines is one of the worldwide trends for global decarbonization goals. However, despite the problems of adaptation of the existing assets for the use of hydrogen, little has been studied about its effects on gas turbine generation systems that operate in tropical climatic conditions where temperatures are higher than 30 °C, and relative humidity reaches values higher than 80%.The gas turbine generator plant with steam injection and cooled air inlet studied consisted of a General Electric LM5000 gas turbogenerator composed of a low-pressure compressor, high-pressure compressor, combustion chambers, turbine, and generator. The steam injection system comprises a heat recovery steam generator and two MUP pumps. The air-cooling system comprises two electric coolers, a cooling tower, two pumps, a cooling coil, two evaporators in series, and two condensers in parallel. The air-cooling system allows for reaching the minimum temperature of 8.8 °C. Plant with Stig cycle in ISO conditions (15°C and 60% RH) produces 52 MW with a thermal efficiency of 43%. The atmospheric conditions in the geographical location of the power plant are, on average, 32°C and 80% relative humidity at sea level. Therefore, the plant with the Stig cycle under local operating conditions produces a power of 44.4 MW with a thermal energy efficiency of 41.6 %. A simulation was conducted in a Stig cycle generation system with a gas turbine, steam injection in the combustion chamber, and cooling air at 8.8°C at the compressor inlet. The system is set to produce 44.4 MW for fuel mix ranges between 0–50% hydrogen. The study results showed that for every 5% by volume of hydrogen added to the H2-natural gas mixture, 5.6% kJ/m3 of energy is lost. Thermal efficiency decreases an average of 2.67% for every 10% increase in hydrogen, which forces an increase in the volume of the fuel mixture to generate the same power. For a percentage of 20% by volume of H2 in the fuel mixture, there are increases in global exergy destruction, avoidable exergy destruction, and unavoidable exergy destruction of 21.5%, 16%, and 31%, respectively. In comparison, the exergetic efficiency decreases by 13.7%. The component most affected by the use of the fuel mixture is the combustion chamber, in which exergy destruction increases by 17.8 MW compared to using 100% natural gas. In addition, the combustion chamber suffers an increase in exergy destruction of 29,2% for every 10% increase in the percentage of hydrogen injection in the fuel mixture. For every 10% increase in H2 volume, there is an average increase in the NOx concentration of 0.4% and a 5% decrease in the CO2 concentration.