Recently, special attention has been focused on micro-nano Si3N4/SiC composites due to the exceptional mechanical properties and oxidation resistance displayed by these advanced materials at high temperatures. The aim of this research project is to prepare micro-nano multicomponent ceramics with nano-sized SiC inclusions in microcrystalline Si3N4 grains by the in-situ crystallisation of amorphous polysilazane-derived bulk ceramics. The polysilazane to ceramic transformation allows to produce Si3N4/SiC composites at unusually low temperatures and to design its microstructure. One task of this project is to assess which appropriate pyrolysing conditions of the polysilazane polymer influence the carbon content of the final ceramic powder. Then, sintering of this polysilazane-derived Si-C-N powder with the desired carbon content enables to gain control over both the localisation and the volume fraction of the nano-sized SiC particles in the microstructure. The SiC dispersion is known to enhance the mechanical performances, which are on the other hand affected by the sintering aids used. Therefore, by lowering the amount of the sintering aids added, it is expected to improve significantly the high-temperature mechanical properties and the oxidation resistance. This latter point is of special interest with respect to the industrial development of novel advanced ceramics for applications in the field of cutting tools, turbine components and air and spacecraft devices.