A range of porous nitride ceramics, including silicon nitride and SiAlON, with a variety of porosity and pore size and morphology have been fabricated, by different techniques such as partial sintering (PS), partial hot-pressing (PHP), restrained sintering by reaction bonding (RSRB), slip casting, reaction sintering, etc. Whisker-like grains were developed in the Si3N4 ceramics, which lead to outstanding mechanical properties and permeability. No grain boundary glass phase was observed in the SiAlON ceramics, even with minor Y2O3 additions. This resulted in them showing outstanding corrosion resistance.