This study systematically investigated the application of a turbocharger system to a hydrogen spark ignition engine to extend operating limitations under high loads. The exhaust system of a commercial 2.4-L natural aspiration spark ignition engine was modified by adopting a turbocharger system. Engine test speeds were 2000-6000 rpm at intervals of 1000 rpm. The intake pressure was fixed for each experimental case, however, the quantity of hydrogen and spark advance timings were varied before the back-fire occurred. High load conditions under natural aspiration and turbocharging conditions were compared. The results indicated that distinctly higher boosts with the turbocharging system helped extend high load conditions, however, the high exhaust pressure obstructed the increasingly high load conditions under high speeds. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.