[EN] Hydrogen is one of the most promising alternative fuels for the transportation industry. The use of hydrogen to enable lean burn in internal combustion engines is an attractive solution for reducing CO2 emissions from two points of views: the substitution of carbon-based fuels and the increased thermal efficiency due to lean operation. Combining this strategy with the passive pre-chamber ignition system with gasoline/hydrogen blends is even more interesting. The main limitations of the passive pre-chamber concept in a high compression ratio spark-ignition engine were shown through engine experiments. A numerical study was then performed to evaluate the chance of extending the dilution limit by using hydrogen along with this technology. Results show how the use of hydrogen provides considerable benefits in the main chamber combustion process by enhancing the thermo-chemical properties of the mixture, increasing the flame speed, and improving the flame structure. Using an adequate gasoline-hydrogen blend proved to enable optimum burning rates at lean conditions, leading to a relevant thermal efficiency gain. Ministerio de Economia, Industria y Competitividad, Gobierno de Espana, Grant/Award Number: TRA2017-89139-C2-1-R; Universitat Politecnica de Valencia, Grant/Award Number: FPI-S1-2019-0033