We present a study on amorphous SiO/SiO 2 superlattice performed by grazing-incidence small-angle X-ray scattering (GISAXS). Amorphous SiO/SiO 2 superlattices were prepared by high-vacuum evaporation of 3nm thin films of SiO and SiO 2 (10 layers each) onto Si(100) substrate. After the deposition, samples were annealed at 1100°C for 1h in vacuum, yielding to Si nanocrystals formation. Using a Guinier approximation, the shape and the size of the crystals were obtained. The size of the growing nanoparticles in the direction perpendicular to the film surface is well controlled by the bilayer thickness. However, their size varies more significantly in the direction parallel to the film surface.