The last CO clean-up step based on the preferential oxidation (CO-PROX) can lead to a reduction of the CO concentration in the hydrogen-rich gas derived from hydrocarbons reforming down to at least 10 ppmv or below, so as to enable its direct feeding to standard PEM fuel cells. In this paper, a screening of powder Pt-based catalysts for CO preferential oxidation reaction was carried out: then the more active catalyst (1% Pt on 50% 3A zeolite and 50% gamma-Al2O3, i.e. 1% Pt-MIX) was deposed by precursors solution spraying followed by in situ combustion synthesis (SCS) in a micro-channel metal plate reactor and the obtained structured system was tested with a synthetic feed stream simulating the WGS outlet composition. The 1% Pt-MIX catalyst was laid out on metal plates previously coated with thin gamma-Al2O3 layer (15 mu m thickness) by plasma spray technique to improve the catalytic material adhesion. A study was then carried out at lambda=2O(2)/CO =4 by varying the GHSV and the superficial catalyst load in a range values characterized by a satisfactory performance for a CO-PROX prototype reactor. The following results were, in fact, obtained with a catalyst load of 0.50 mg cm(-2): with GHSV equal to 2000 h(-1) and 4800 h(-1) the complete CO conversion (residual CO concentration less than 2 ppmv) with simultaneous O-2 conversion equal to 1 was obtained in the temperature range 194-214 degrees C and 215-225 degrees C, respectively. (C) 2009 Elsevier B.V. All rights reserved.