In order to survive at media-term, diesel engines need a new approach for the use of the new fuel
portfolio and to control the exhaust gas emissions. Hydrogen has been proposed as an alternative
due to its excellent combustion properties, which could improve the combustion performance and
emissions of internal combustion engines [1, 2]. The main drawback is that the location of a hydrogen
cylinder inside the vehicles implies space and risk problems. Therefore, it could be produced on
board and released into the air-intake of any biofuels fed to diesel engines. For that, the required
optimized amount of hydrogen must be known, studying all engine parameters and emission in
different driving modes for the establishment of the engine regions of operation in which partial
replacement of fuel by hydrogen is effective as a bridged technology.