NOVELTY - Fuel processor (100) for forming hydrogen comprises: integrated steam reformer/combustor (51) to receive steam/fuel mix and air/fuel mix; heat exchangers (41, 42) before and after assembly to receive combustion and reforming products, respectively; steam generator (43) receiving heat from reforming products; water gas shift reactor (52) at 250-500 degrees C and steam generator (44) receiving heat from its products; water gas shift reactor (53) at 150-400 degrees C and heat exchanger (45) for its products; reactor for selective carbon monoxide oxidation (54) and heat exchanger (46) cooling its products.    USE - As a fuel processor for production of hydrogen from a fuel source (claimed), for feeding low temperature fuel cells.    ADVANTAGE - The fuel processor is comprised of four reactors, and a multitude of heat exchangers, and achieves a very high degree of heat integration and very high efficiency. To increase efficiency, the reforming reactor is of a heat exchanger type and is comprised of a heat integrated reformer/combustor assembly, where the two sections are separated by a thin metal partition, and are in thermal contact to facilitate the efficient transfer of heat from the combustion to the reforming section; and a fuel and steam mixture is supplied to the reformer to be reformed, and a fuel and air mixture is supplied to the combustor to be combusted. All four reactors and several heat exchangers can be placed inside a single shell, resulting in a very compact fuel processor well suited for distributed hydrogen generation. The fuel processor also comprises a high temperature water-gas-shift (WGS) reactor, a low temperature WGS reactor and a methanation reactor. The fuel processor further includes a series of heat exchangers to exchange heat between different streams of the process.    DETAILED DESCRIPTION - A fuel processor (100) for production of hydrogen from a fuel source, comprises within a single housing: an integrated steam reformer/combustor assembly (51) configured to receive a steam/fuel feed mix to be reformed in the assembly and an air/fuel mix to be combusted in the assembly; a heat exchanger (41) placed before and in fluid connection with the assembly configured to receive the combustion products and transfer heat to the reformer feed; a heat exchanger (42) placed after and in fluid connection with the assembly configured to receive the reforming products and transfer heat to the reformer feed; a steam generator (43) receiving heat from the reforming products and generating steam; a reactor (52), where the water gas shift reaction takes place at 250-500 degrees C; a steam generator (44) receiving heat from the water gas shift reaction products and generating steam; a reactor (53), where the water gas shift reaction takes place at 150-400 degrees C; a heat exchanger (45) cooling the water gas shift reaction products; a reactor (54) where the selective CO oxidation or methanation reactions take place; and a heat exchanger (46) cooling the selective carbon monoxide (CO) oxidation or methanation reaction products. The fuel processor further comprises a heat exchanger transferring heat between the combustion products and the fuel feed to the reformer; a heat exchanger transferring heat from the combustion products and generating steam; a heat exchanger transferring heat between the combustion products and the air feed to the combustor; a heat exchanger transferring heat between the combustion products and water or air to produce higher temperature water or air; a separator separating condensed water for the cooled combustion products and recycling the water back to the process; a separator separating condensed water for the cooled reforming products and recycling the water back to the process; and a separator separating condensed water for the cooled reforming products and recycling the water back to the process.    DESCRIPTION OF DRAWING(S) - The figure shows the fuel processor.    Heat exchangers (41, 42, 45, 46)    Steam generators (43, 44)    Reformer/combustor assembly (51)    High temperature water-gas-shift (WGS) reactor (52)    Low temperature water-gas-shift (WGS) reactor (53)    Carbon monoxide selective oxidation reactor (54)    Fuel processor. (100)