NOVELTY - Several heat exchangers (14) are arranged in series for super heating a hydrocarbon fuel so as to provide super heated fuel. Several water injection points (16) are arranged at the downstream side of respective heat exchangers for mixing water with superheated fuel, so as to provide hydrocarbon fuel stream mixture.    USE - For preparing fuel.    ADVANTAGE - Installation space of the fuel cell system is reduced. Carbon deposition and catalyst deactivation in fuel cell system are reduced. Humidity or dew point of air is increased.    DETAILED DESCRIPTION - The fuel cell system further includes several heat exchangers arranged serially for heating stream of air using waste heat from polymer electrolyte membrane (PEM) made fuel cell and fuel processor system so as to provide heated air stream, and several water injection points are arranged at the downstream of respective heat exchangers for mixing water so as to provide humidified air stream.    An INDEPENDENT CLAIM is also included for the fuel processing method which involves heating hydrocarbon fuel or methane to about 189-260 degreesC in fuel processing system (10) which converts hydrocarbon fuel to hydrogen rich gas stream for fuel cell, and liquid water is added to the hydrogen rich gas stream to a temperature of 189 degreesC so as to provide gas stream mixture. The above process of heating and mixing of hydrogen fuel and liquid water is repeated until the molar ratio of water to hydrocarbon fuel is 3. The process also involves heating of air stream using waste heat from fuel cell fuel processing system so as to provide heated stream to which liquid water is added so as to obtain humidified air stream and the process is repeated until the molar ratio of steam to fuel is 3, so as to obtain final humidified air stream with a dew point.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of the fuel cell system.    Fuel processing system (10)    Heat exchangers (14)    Water injection points (16)