Spincoating colloidal solutions of monodisperse nanoparticles onto flat silica supports offers a facile and flexible way to produce model catalysts with well defined catalyst loading and particle size. By spincoating iron oxide (magnetite) nanoparticles with varying particle diameter we produce a model system for iron based Fischer-Tropsch catalysts. In this proof of principle study we employ a combination of surface spectroscopy (XPS) and transmission electron microscopy (TEM) to investigate the changes in surface chemistry and morphology of the model catalysts upon catalyst pretreatment and exposure to syngas. (C) 2010 Elsevier B.V. All rights reserved.