At present, less than 7% of the hydrogen produced in the U.S. is delivered to users as “merchant” hydrogen. The balance is produced and used as “captive” hydrogen as a chemical intermediate. In the future it is probably that this pattern will change and that the predominant use for hydrogen will be as fuel. In this paper the discussion of environmental and safety considerations related to the use of hydrogen is focused primarily on its use as a fuel for autos, trucks and buses, and for aircraft. The objective is to bring some of the interesting generalities of the subject to the attention to those who are just acquiring an interest in the potential of hydrogen, as well as for those specialists in hydrogen technology who may not have given much thought to these considerations.