Silicon-on insulator (SOI) structures obtained by direct bonding of wafers using a hydrogen cutting technology were characterized by high-resolution X-ray diffraction. The as-bonded SOI structures indicate some fluctuation of the lattice constant values due to hydrogen-related defects and radiation defects still present in the silicon film. The bonded interface is nonuniform, and the strain in the top silicon layer is high. Annealed SOI has a strain-free top silicon layer with a good Si/SiO2 interface.