In response to global warming and pollution, the use of alternative fuels in diesel engines is becoming increasingly important. The purpose of this research is to evaluate the effects of hydrogen and ammonia additions to diesel fuel on carbon emissions and energy and the exergy efficiency of diesel engines and also to evaluate sustainability. In the study, the effects of adding 5%, 10% and 15% of both hydrogen and ammonia to conventional diesel fuel on specific fuel consumption, carbon emissions, energy, exergy and sustainability index were examined parametrically. Ammonia and hydrogen fuel reduce CO2 emissions because they are carbon-free. As a consequence of the research, it was found that, compared to ammonia addition, increasing hydrogen addition lowered specific fuel consumption while decreasing engine performance. The findings obtained show that mechanical energy and exergy values increase by 5.5% in the case of hydrogen addition and decrease by approximately 1.1% in ammonia addition. It was determined that the thermal efficiency and sustainability index increased in the case of hydrogen addition and decreased in the case of ammonia addition. The exergy efficiency was estimated to be 63.37%, an increase of around 2.3% over pure diesel. The highest sustainability index (SI) and exergetic performance coefficient (EPC) values were determined 2.73 and 1.63, respectively In line with the first and second law analyses, the usability of ammonia and hydrogen in diesel engines was evaluated thermodynamically.