My research is concerned with relationships between microstructure and properties of hard inorganic materials. The research involves the application of different scanning and transmission electron microscopy techniques for imaging and microanalysis. The work covers three areas of material's science: (i) development and stability of nano-/microstructures, (ii) toughening and strengthening mechanisms, and (iii) deformation mechanisms. The development of nano-/microstructure under different processing and testing conditions is characterized by high-resolution imaging and microanalysis, and the results are related to different parameters in the fabrication process and to the behaviour of the material under mechanical and thermal load. A significant part of the research has been concerned with the development of fine-scale microstructure during sintering and crystallisation processes in ceramic and glass-ceramic materials. The mechanical and chemical behaviour of ceramic matrix composites, including nanocomposite materials, has been investigated, and the role of the internal interfaces in these materials has been addressed. My current research interest also includes the structure and properties of polycrystalline cubic boron nitride materials and cemented carbides for cutting tool applications.