Abstract: A ceramic material includes at least 90% of a single phase silicon aluminum oxynitrite having the general formula:--Si.sub.6.sub.-z Al.sub.z N.sub.8.sub.-z O.sub.z --where z is greater than 0 and less than or equal to 5.One method of producing the ceramic material involves sintering a mixture including not more than 75% by weight of high active surface area alumina powder of particle size less than 10 microns and silicon nitride powder of particle size less than 20 microns.In another method of producing the ceramic material, a mixture of silicon and alumina powders of particle size less than 20 microns is nitrided at a temperature between 1250.degree. C and 1600.degree. C. The proportions of silicon and alumina in the mixture being nitrided are such that the atomic ratio of silicon to aluminium is not less than 1:3.