Silica-supported iron nanocatalysts for Fischer-Tropsch Synthesis (FTS) were prepared using the modified colloidal method in the presence of surfactants in an organic medium. The iron loading on silica support was varied at 3, 5 and 6 wt.. The samples were characterized by XPS, TPR and TEM. The presence of Fe2O3 on the silica support was confirmed by XPS. TPR analysis showed that the increase in Fe loading caused the first reduction temperature of the nanocatalysts to shift to a higher temperature. TEM analysis revealed that the iron nanoparticles were not uniformly distributed on the silica support. The size of iron nanoparticles ranged from 4 to 20 ran. For the 3 and 5 wt. Fe/SiO2, the size of the iron nanoparticles were mostly in the range of 1-5 nm, whereas for the 6 wt, most of the iron nanoparticles (74) were in the range of 6-10 nm. © 2011 Asian Network for Scientific Information.