This article presents a comprehensive analysis of hydrogen combustion issues in reciprocating engines and the potential for numerical modeling in the context of developing low-emission technologies. The advantages and technical and environmental challenges associated with its use are presented, with particular emphasis on nitrogen oxides emissions, ignition control, and material requirements. This article takes a closer look at how advanced numerical modeling methods – such as computational fluid dynamics, large eddy simulation, and direct numerical simulation – help better understand the hydrogen combustion process in piston engines. These methods reveal flame behavior, combustion processes, and associated emissions. The authors compare various computational programs and demonstrate how simulation can aid in combustion chamber design, ignition timing, and mixture tuning. The article summarizes the most important findings in this field and outlines the direction hydrogen technology is headed. The analysis indicates that hydrogen addition (typically 10–30% by volume) can enhance combustion stability and indicated thermal efficiency under lean conditions, although excessive hydrogen fractions do not guarantee further performance gains. At the same time, challenges related to NOₓ formation, pre-ignition, and mixture control require advanced injection strategies and precise combustion calibration. The reviewed studies confirm that high-fidelity numerical modelling is essential for capturing preferential diffusion and turbulence–chemistry interactions, making it a key tool in the optimization of hydrogen-fueled piston engines.