This article describes the focused ion beam (FIB)-tomography as a high-resolution three-dimensional (3D) technique to study the morphology of polymer/clay nanocomposites. To establish the structure -property relationship of such composite material, it is very important to visualize the 3D-structure and distribution of clay particles in the polymer matrix. The sequential two-dimensional sectioning by FIB, followed by imaging of dispersed silicate layers using high-resolution scanning electron microscope, and computer reconstruction can show the degree of dispersion of silicate layers in 3D-space. (C) 2010 Elsevier Ltd. All rights reserved.