Abstract: A method of operating an internal combustion engine under high charge dilution conditions using a hydrogen-rich fuel is disclosed. The high charge dilution conditions are attained by diluting the hydrogen-rich fuel with gases such as excess air or recycled exhaust gas. The mixture to be charged to the combustion chamber is thoroughly mixed before it is introduced into the combustion chamber while the combustion chamber maintains a substantially quiescent state such that the charge mixture is introduced with an angular momentum lower than that of a typical low emission engine. The result is an internal combustion engine with both high efficiency and low emissions, particularly, low NOx emissions.