A compact and highly efficient natural gas fuel processor for I-kW residential polymer electrolyte membrane fuel cells (PEMFCs) has been developed at the Samsung Advanced Institute of Technology (SAIT). The fuel processor, referred to as SFP-2, consists of a natural gas reformer, a water-gas shift reactor, a heat-exchanger and a burner, in which the overall integrated volume including insulation is exceptionally small, namely, about 141. The SFP-2 produces hydrogen at 1000 1 h(-1) (STP) at full load with the carbon monoxide concentration in the process gas below 7000 ppmv (dry gas base). The maximum thermal efficiency is similar to 78% (lower heating value) at full load and even similar to 72% at 25% partial load. This fuel processor of small size with high thermal efficiency is one of the best such technologies for the above given H-2 throughputs. The time required for starting up the SFP-2 is within 20 min with the addition of external heating for the shift reactor. No additional medium, such as nitrogen, is required either for start-up or for shut down of the SFP-2, which is an advantage for application in residential PEMFC co-generations systems. (c) 2006 Elsevier B.V. All rights reserved.