An investigation has been computationally carried out to study the effects of intake hydrogen enrichment on combustion characteristics and engine performance in a light-duty diesel engine. The combustion of H 2 -diesel has been modeled using a reduced chemical mechanism consisting of 76 species and 349 reactions. In order to maintain the engine operating conditions at a constant speed and load, the addition of the H2 rate has been accompanied by the decrease of diesel fuel mass injected in each cycle. This has been accomplished by substituting 20% of the diesel fuel mass for every 10% H2 addition. Moreover, different Exhaust Gas Recirculation (EGR) strategies have been applied to control the formation of NOx emissions. In this study, the effects of hydrogen additions of 0%, 10%, 20%, 30%, and 40% at constant engine operating speed with EGR rates from 0-40% have been studied. The Computational Fluid Dynamics (CFD) results have revealed that, in a constant EGR rate, when the H 2 addition was increased up to 30%, the in-cylinder pressure gradually increased, and then decreased when the hydrogen addition was increased to 40%. It has been found that the application of an EGR strategy accompanied by a proper H 2 addition is an effective in-cylinder technique for controlling the oxides of nitrogen (NOx) and particulate matter (PM) emissions while maintaining the engine operating conditions.