This paper presents an experimental investigation of a fuel processor consisting of a JP-8 autothermal reforming (ATR) reactor and a surrogate-fed CO-cleanup train. The CO-cleanup train, comprising a water-gas shift (WGS) and two preferential oxidation (PROX) reactors, was tested as an integrated reactor train. A finned-wall ATR reactor was examined for light-off behavior and for steady-state product distribution, upon which the CO-cleanup train was designed. The thermal and chemical transient analysis during catalyst ignition indicated that the fuel undergoes deep oxidation to CO2 and H2O until 80% of the catalyst bed is ignited, followed by a significant rise in synthesis gas production. The WGS and PROX reactors were tested individually with the objective of identifying operating regimes for maximum CO removal. The PROX reactor train, consisting of two identical reactors connected in series, reduced the CO concentration from 1% to less than 6 ppm. The PROX-1 and PROX-2 reactors were compared in order to elucidate the CO conversion and selectivity loss observed for PROX-1 at T > 250 degrees C and for PROX-2 at temperatures between 120 and 145 degrees C, suggesting that the CO conversion decrease follows different controlling mechanisms for the two reactors. Finally the CO-cleanup train was tested as three reactors in series, illustrating the critical effect that the CO conversion in the water-gas shift reactor has on the downstream PROX reactors. The CO-cleanup train was operated at the maximum conversion, demonstrating the capability to decrease the CO concentration from 8% to single-digit ppm level.