Colloidal processing, which is composed of the dispersion of starting powders in liquid media and following consolidation, is superior to general dry pressing in the control of densities and microstructures of green and sintered compacts. The dispersion characteristic of the nanometre to submicrometre-sized powders in aqueous suspensions is greatly dominated by van der Waals attraction force and electrostatic repulsive force between colloidal particles. The critical solid content for highly viscous colloidal liquid, which was determined from the analysis of rheological properties, and increase of packing density during drying were compared with calculated metastable phase diagrams for one-component colloidal systems. The theoretical analysis on the pore structure in a powder compact was made with an fcc model (face-centred cubic close-packing) of hierarchically clustered spherical particles. The derived theory can reveal the pore volume and pore size distribution of 1st generation pores (contained within clusters of primary particles) and 2nd or 3rd generation pores (contained among the 1st or 2nd generation particle clusters).