NRMM, stage V engines are already mandatory but at expense of increased prices that probably many industrial users will refrain from buying, keeping older equipment running. In this work was conducted an experimental comparative study on the effects of partial replacement of fossil diesel by gaseous hydrogen in fuel and volumetric efficiency, energy substitution and exhaust emissions of a dual fuel internal combustion engine (ICE). The experiments were conducted at fixed speeds of 1000, 1250, 1500, 1750 and 2000 rpm at no load. The hydrogen was injected in admission port with flows ranging from 1 to 15 l/min. The results indicated that adding hydrogen influenced fuel economy, with savings from 6.2% to 28.2% depending on the engine's rpm. It was also registered an increase in volumetric efficiency of 23.4% with less 50% CO and 83% NOx. Nevertheless, the total energy input decreased 17% at 2000 rpm with 15 l/min of H2.