Micro-channel plates with dimension of 1 mm x 0.3 mm x 48 mm were prepared by chemical etching of stainless steel plates followed by wash coating of CeO2 and Al2O3 on the channels. After coating the support on the plate, Pt, Co, and Cu were added to the plate by incipient wetness method. Reaction experiments of a single reactor showed that the micro-channel reactor coated with CuO/CeO2 catalyst was highly selective for CO oxidation while the one coated with Pt-Co/Al2O3 catalyst was highly active for CO oxidation. The 7-layered reactors coated with two different catalysts were prepared by laser welding and the performances of each reactor were tested in large scale of PROX conditions. The multi-layered reactor coated with Pt-Co/Al2O3 catalyst was highly active for PROX and the outlet concentration of CO gradually increased with the O-2/CO ratio due to the oxidation of H-2 which maintained the reactor temperature. The multi-layered reactor coated with CuO/CeO2 showed lower catalytic activity than that coated with Pt catalyst, but its selectivity was not changed with the increase Of O-2/CO ratios due to the high selectivity. In order to combine advantages (high activity and high selectivity) of the two individual catalysts (Pt-Co/Al2O3, CuO/CeO2), a serial reactor was prepared by connecting the two multi-layered micro-channel reactors with different catalysts. The prepared serial reactor exhibited excellent performance for PROX. (C) 2007 Elsevier B.V. All rights reserved.