NOVELTY - A fuel processor (10) comprises a structure to have fluid pass through its entire length, and having upstream portion (14) and downstream portion (16), where the upstream portion has larger diameter than the downstream portion; first catalyst supported at the upstream portion; second catalyst supported at the downstream portion, where first catalyst is in fluid communication with second catalyst, and uncoated foam positioned upstream from first catalyst such that first catalyst resides between the foam and the second catalyst.    USE - In reforming of fuel for use in fuel cells.    ADVANTAGE - The processor provide for near complete conversion of fuel, while also ensuring that the catalysts last for at least 5000 start-stop cycles, assuming 10 hours per cycle. The system should also be initiated with an energy input (in BTUs) which is not greater than 1-3 (preferably less than 1)% of the total energy produced by the system/method during each cycle. The system vastly increases the catalyst life in autothermal and partial oxidation reformer-based processors. An advantage of the processor is that the different catalysts are each heated to their optimum operating temperature to concomitantly facilitate chemical conversions. The processor provides a conduit for both heat and fluids to traverse through the zones, hence establishing fluid communication between the temperature zones. This structure provides device for dissipating thermal energy generated in oxygen-rich upstream conversions to protect more heat sensitive, downstream noble-metal catalysts. The processor overcomes the problem of catalyst durability resulting from the high temperatures encountered in autothermal and partial oxidation reactors, yet has excellent durability and is of simple design. The system allows the oxidation reactions (i.e. light off) to begin as low as about 480 degrees C in the presence of oxygen. The downstream portion of the processor must operate at low oxygen concentrations to avoid rapid oxidation reactions that will produce hotspots on the catalyst surface leading to deactivation.    DETAILED DESCRIPTION - A fuel processor (10) comprises a structure to have fluid pass through its entire length, and having upstream portion (14) and downstream portion (16), where the upstream portion has larger diameter than the downstream portion; first catalyst supported at the upstream portion; second catalyst supported at the downstream portion, where first catalyst is in fluid communication with second catalyst, and uncoated foam positioned upstream from first catalyst such that first catalyst resides between the foam and second catalyst. The processor additionally comprises fuel inlet in thermal communication with upstream portion. The first catalyst is oxidation catalyst and second catalyst is reforming catalyst.    DESCRIPTION OF DRAWING(S) - The figure shows schematic view of catalyst system encapsulated by housing.    Catalyst system (10)    Housing (11)    Proximal end (11p)    Distal end (11d)    Catalyst support (12)    Upstream portion (14)    Downstream portion (16)    Uncoated portion of the catalyst (18)    Edge (19)    Passageway (22)