An ordered mesoporous silica (SBA) was used to assist space-confined formation of FePt nanoparticles. ordered mesoporous oxides were found to be excellent templates for the preparation of well-defined nanoparticles, nanowires, and three-dimensional nanostructures. It was found that sintering agglomeration can be minimized and transformation into ferromagnetic tetragonal FePt is achieved, without a significant increase of the particle diameter, due to the high temperature stability of the surrounding oxide matrix. It was also found that the growth of the particles was controlled by the pore size of the oxide matrix. Two different strategies were developed for the integration of FePt nanoparticles and in both cases FePt/SBA15 composites were prepared by incipient impregnation of ordered mesoporous silica.