Spherical model catalysts consisting of SiO2-sphere-supported iron nanoparticles were prepared using the colloidal synthesis approach, the reverse microemulsion and the ammonia deposition methods. Amongst these synthesis methods, the colloidal synthesis approach was found to be the most promising synthesis route for the Fe/SiO2 model catalysts. The modified colloidal synthesis method produced nearly monodisperse spherical-shaped iron oxide nanoparticles with average diameters of 6.2 ± 0.9 nm on the SiO2 spheres. Morphological changes were observed on the spherical Fe/SiO2 model catalysts after the Fischer-Tropsch synthesis (FTS) reaction. © 2009 American Institute of Physics.