A method of generating a H.sub.2 rich gas from a fuel includes supplying a mixture of molecular oxygen, fuel, and water to a fuel processor, and converting the mixture of molecular oxygen, fuel, and water in the fuel processor to the H.sub.2 rich gas. The fuel has the formula C.sub.nH.sub.mO.sub.p where n has a value ranging from 1 to 20 and is the average number of carbon atoms per mole of the fuel; m has a value ranging from 2 to 42 and is the average number of hydrogen atoms per mole of the fuel; and p has a value ranging from 0 to 12 and is the average number of oxygen atoms per mole of the fuel. The molar ratio of molecular oxygen supplied to the fuel processor per mole of fuel is a value ranging from about 0.5x.sub.0 to about 1.5x.sub.0, and the value of x.sub.0 is equal to 0.312n-0.5p+0.5(.DELTA.H.sub.f, fuel/.DELTA.H.sub.f, water) where n and p have the values described above, .DELTA.H.sub.f, fuel is the heat of formation of the fuel, and .DELTA.H.sub.f, water is the heat of formation of water.
 The United States government has rights in this invention pursuant to Contract No. W-31-108-ENG-38 between the United States Department of Energy and the University of Chicago representing Argonne National Laboratory.