Hydrogen represents a promising low-carbon fuel that enables the decarbonisation of transportation without the need for a radical replacement of the piston combustion engines. The presented study analyses the influence of adding hydrogen to the intake air in a turbocharged spark-ignition engine, focusing on fuel combustion process and on gaseous pollutant emissions. The experimental part of this work was complemented by the numerical simulations in order to validate the observed trends. The obtained results show that hydrogen increases the maximum engine cylinder pressure, accelerates the combustion process of fuel-air mixture, as well as it improves the heat release efficiency, thereby shortening the combustion duration and enhancing overall engine efficiency. A reduction in emissions was also observed. The findings support the use of hydrogen as an additive fuel during the transitional period towards zero-emission mobility. They also highlight the need for further research in optimizing of fuel combustion process at higher hydrogen proportions and under various engine load conditions.