Hydrogen generated from renewable sources is an eco-friendly fuel that can be used in automotive industry or for energy generation purposes. Hydrogen is a high-energy content gas and its carbonless chemical structure can provide significant benefits of high thermal efficiency and near zero or very low carbon emissions when combusted with other fuels. In this study, the implementation of hydrogen fuel was tested at low and medium operating loads in a heavy-duty hydrogen-diesel dual-fuel engine. The paper provides a detailed experimental analysis of the effects of hydrogen energy share ratio and various combustion strategies such as exhaust gas recirculation, diesel injection pressure and diesel injection patterns. At low load conditions, engine operation with an H-2 energy share ratio of up to 98% was achieved without any engine operation implications. This condition provided a simultaneous reduction of carbon and NOx emission of over 90% while soot emissions were dropped by 85% compared to the conventional diesel-only operation. At medium load, the increased NOx emission due to the high energy content of hydrogen fuel was found to be the primary challenge. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.