High-resolution 3D-imaging techniques are now widely used in materials science, and for the 3D microstructural characterisation of materials as diverse as polymers, ceramics, metals, composites, foams and cellular materials, concrete, rocks, wood, etc., they are feasible at the micro- and nanometer scales. Furthermore, as some techniques are nondestructive (at least for the studied sample), 4D-imaging is possible, following the 3D microstructural changes of a sample subjected to mechanical deformations, temperature variations, chemical reactions, etc. Continuous advances in experimental techniques provide a growing flux of data, significantly modifying the way in which the relation between microscopic structure and macroscopic properties is explored. These new possibilities create new demands in terms of analysis and modelling methods. The development of reliable and effective laboratory equipment and the increase in computational power lead to a noticeable diffusion of these techniques through academic and industrial laboratories, where a large variety of materials are studied.This special issue of Advanced Engineering Materials offers a selection of contributions presented during the 1st International Conference on 3D-Imaging of Materials and Systems (3D-IMS2008) that took place at Carcans (near Bordeaux, France) on the 8–12 September, 2008. All the manuscripts were subjected to a peer-review procedure by the scientific committee of the conference, and the 13 accepted papers are included in this special issue.3D-IMS2008 was the first conference of a series that aims to gather experts in 3D image acquisition, 3D image analysis, and 3D image applications to exchange experiences in these different fields and to improve the quality of the results that can be obtained. Sessions covered a variety of topics related to data acquisition, data analysis, and final applications for which the 3D nature of the results improves the knowledge of a specific material or system. A second conference in this series, 3D-IMS2010, took place at Hourtin (also near Bordeaux) on the 6–10 September, 2010. The following conference will be held at Ghent (Belgium) in July 2013. This will be the first conference of a new series merging 3D-IMS and GEOX, a series of International Workshops on X-ray CT for Geomaterials (2003, Kumamoto, Japan; 2006, Grenoble, France; 2010, New Orleans, USA).The subheading of 3D-IMS2008 was “Acquisition - Analysis - Applications”. The papers presented in this special issue have been selected to illustrate, by representative examples, the research activities under development in these three domains. This is only a very fractional view, but some leading tendencies are outlined. Concerning acquisition, it is shown that synchrotrons are always privileged places for innovative imaging techniques. At very high resolution, the fast-growing importance in materials science of two techniques, 3D-TEM and FIB-SEM, is highlighted. Analysis of an increasing number of very large 3D images is challenging: huge developments are required to extract relevant topological and morphological parameters characterizing complex 3D microstructures of real materials. Numerical methods (FEM for instance) are commonly used to infer values of physical properties strongly linked to the microstructure, but efficient procedures must be developed to integrate into the numerical grids the significant characteristics contained in the 3D voxelized images. Because of the availability of 4D acquisitions, the well known digital image correlation method has been generalized to digital volume correlation, and the potential of this method suggests fundamental changes in the micromechanical approach to the study of complex materials. Fields of application are numerous. Metallic materials are frequently studied through 3D imaging, and several examples are presented, but less common materials like snow or catalysts are also present. The use of 3D imaging to study transport in porous media is increasing in popularity, helping, in some cases, to better understand material degradation during use due to irradiation or chemical reactions.On behalf of the organizing committee, I would like to express our gratitude to all the attendees for contributing to the success of 3D-IMS2008 and the following conferences. The financial support of the CNRS, the Bordeaux 1 University, the Material Institute of Bordeaux, and the Région Aquitaine is gratefully acknowledged.< Leer menos