A composite was prepared from a prior preform by chemical processing of reactive precursor powders synthesized from coprecipitated mixtures of an aluminium silicate and aluminium hydroxide, which was prepared using aluminium salts in solution and a diamine as base precipitant and coupling chemical agent. This is also the organic source for carbothermal reduction. The powder was compacted by cold-pressing and the preform thermally treated under nitrogen flow to facilitate nitridation and carbothermal reduction. A subsequent controlled oxidation process was used to prepare the composite. The final sintered composite comprised layers of mullite, mullite and alumina, beta-SiAlON and silicon carbide. The presence of particles (mullite-sialon) and fibres (sialon-silicon carbide) in the composites was considered very attractive from the point of view of mechanical, thermal and electrical behaviour.