The effect of ruthenium (Ru, 0.4 wt %) as a promoter on silica-supported iron and cobalt nanocatalysts (similar to 3 wt % each) for syngas (H-2 and CO) conversion to higher alkanes was studied in a silicon microreactor. Fe-Co/SiO2 catalysts with and without Ru were synthesized by a sol-gel methods. The high specific surface area (325 m(2)/g) from BET analysis can be attributed to the porous structure of silica supported by its SEM images. The FE-STEM image indicated that the catalyst particle size is < 10 nm. The magnetic studies of Co catalysts using a vibrating sample magnetometer suggest that Ru does not influence the reduction of cobalt oxide to cobalt, the active form of Co catalysts in silica. The highest conversion of CO (similar to 78%) was observed with a Ru-Fe-Co/SiO2 catalyst at 220 degrees C, 1 atm, total flow rate of 0.4 seem, and H-2/CO ratio of 3:1 in microreactors containing 25 mu m channels. The addition of Ru to the Fe-Co/SiO2 catalyst increased CO conversion by 16% but lowered selectivity to propane by 10%. The catalysts remained active after. 25 h of reaction, although the magnetic properties indicated that similar to 85% of metal nanoparticles formed non-ferromagnetic species.