Defects in the Si layered structures, Si:H(D), prepared by implantation with H 2 + /D + , and their changes resulting from the treatment under enhanced pressure (HP), were investigated by X-ray diffraction and transmission electron microscopy (XTEM). Such treatment affects out-diffusion of hydrogen (deuterium) as well as the shape and concentration of the H(D)-filled cavities. The relation between X-ray and XTEM results is discussed.