In recent years, the automotive industry has been clearly moving toward carbon neutrality, and internal combustion engines that use fossil fuels are becoming unsustainable. On the other hand, hydrogen engines do not emit CO2 during operation, and if the working gas of a hydrogen engine is replaced with argon and oxygen (by removing the produced water and circulating argon), the thermal efficiency can be dramatically improved. However, when the high adiabatic compression temperature of argon is added to the inherent knocking problems of hydrogen engines, the knocking problem becomes even more pronounced, and no effective solution to avoid knocking has been found to date. In this study, the effects of argon, oxygen, and hydrogen concentrations on combustion and power, respectively, were investigated to determine the effects of working gas composition on combustion and knocking, and the control effects of oxygen rich or hydrogen rich on knocking was investigated.