Encyclopedia of Liquid Fuels contains information on liquid fuels to be used as rocket propellants. In the general subject area of fuels for rocket propellants, there are both liquid fuels and solid fuels in use. Solid fuels serve a dual purpose as binders in solid rocket propellants and are not included in this book. Therefore the title of this book could not be Encyclopedia of Rocket Propellant Fuels, but the title had to be more specific by limiting the scope to liquid fuels. The choice of liquid fuels with their widely varying hydrogen content has a strong infl uence on the specific impulse of rocket propellant combinations.