Different metallic supports (aluminum foams of 40 ppi, honeycomb monolith and micromonolith of 350 and 1180 cpsi, respectively) have been loaded with a 20%Co-0.5%Re/gamma-Al2O3 catalyst by the washcoating method. Layers of different thicknesses have been deposited onto the metallic supports. The catalytic coatings were characterized measuring their textural properties, adhesion and morphology. These structured catalysts have been tested in the Fischer-Tropsch synthesis (FTS) and compared with a microchannel block presenting perpendicular channels for reaction and cooling. The selectivity depends on the type of support used and mainly on the thickness of the layer deposited. In general, the C5+, selectivity decreased at increasing CO conversion for all of the systems (powder, monoliths, foams and microchannels block). On the other hand, the selectivity to methane increased with the thickness of the catalytic layer due to the higher effective H-2/CO ratio over the active sites resulting from the higher diffusivity of H-2 compared with CO in the liquid products filling the pores. The C5+. selectivity of the microchannels reactor is higher than that of the structured supports and the powder catalyst. (C) 2010 Elsevier By. All rights reserved.