The different preparation methods of ultrafine powders of high melting point compounds (carbides, borides, nitrides, and oxides with melting temperatures higher than 2000-degrees-C) are reviewed. Some properties of these powders are discussed and compared. The consolidation behaviour of these compounds in the nanocrystalline (nc) state is described in detail. Compaction by hot pressing, including high pressures and high temperatures, sintering, and high-energy consolidation methods, is analysed. The microstructure, recrystallization, mechanical and physical properties of nc-carbides, nitrides, and oxides are characterized. Special attention is focused on relationships between structure and properties.