Brazil is aligned with the global effort to combat the worsening of global warming due to anthropogenic emissions of greenhouse gases. In 2021, nearly half of the emissions associated with energy usage in Brazil was originated from the burning of fossil fuels in the transportation sector, with diesel being the primary focus. In this context, this study aimed to experimentally investigate the partial replacement of conventional diesel with hydrogen in a compression ignition internal combustion engine. The objective was to assess how this substitution would impact the engine s performance and, consequently, the emissions produced by a heavy-duty vehicle.To conduct this study, the findings of previous research into the effects of hydrogen addition in compression ignition engines were taken into account. Based on these studies, it was possible to select the vehicle to be used in the tests and establish the testing conditions. In order to estimate the potential emissions reduction, scenarios were defined in which hydrogen would replace up to 30% of the energy used in vehicles with dual-fuel technology. Furthermore, a theoretical study that simulates combustion considering Gibbs Free Energy was carried out as a supplement to the experimental data. The increase in HES and air/fuel ratio had no impact on 𝐻2 emissions. 𝐶𝑂 e 𝐶𝑂2 emissions tended to 0 ppm and decreased by 5% when the HES and the air/fuel ratio increased, respectively. Finally, 𝐻2𝑂 and 𝑁𝑂 emissions increased by 8.33% and decreased with increasing air/fuel ratio and HES, respectively.