This book focuses on the feasibility of operating Spark Ignition engines on hydrogen-ethanol dual fuels. Hydrogen-Ethanol could be the best option of dual fuelling, which not only minimizes all types of exhaust emissions but also has better power outputs, complete and strong combustion and smooth engine operation. However handling, delivery and injection of hydrogen requires additional care.The important improvement of hydrogen addition is to reduce the Specific fuel consumption of ethanol engines.Recent activities on that matter focus on hydrogen blended ethanol engines rather that pure hydrogen combustion engines due to its high costs and research needs. Today, in order to take the advantages of the fossil fuels, which are being consumed rapidly, we need to adapt ourselves to such dual fuel systems. Hydrogen fuel is a very strong candidate for being used in dual fuel applications with ethanol due to a main reason that it has an advantage of being found everywhere. The present book rely on the idea of low emission and high efficiency advantages of hydrogen, which would lead hydrogen blended ethanol engines in the near future.