Manufacture and characterization of a novel ceramic membrane filter for separation processes is presented. Composite membrane filters consisting of a sialon active- layer and silicon nitride support were fabricated using a modified slip casting process followed by a pressureless sintering procedure. The resulting microstructures of the filters were characterized by SEM with a LINK light element X-ray detector. SEM revealed a relatively uniform microstructure with excellent interparticle bonding at the membrane/support interface whilst the EDS analysis showed a homogeneous chemical composition on the membrane surface layers. X-ray diffraction was employed to identify the phases present on the membrane layers. Beta-sialon was identified by XRD as the main phase in the membrane. Crack-free membrane layers less than 40 mum thick were obtained with interconnected pore sizes of about 0.2 to 0.6 mum. Corrosion tests were performed and revealed no measurable signs of degradation in the membrane filters. Water permeability tests showed a high permeability in excess of 8 x 10(-14) m2 and a clean water flux greater than 110 lh-1m-2kPa-1.