The crystallization of pyrolysed chlorine containing polycarbosilanes (PCS) into silicon carbide is suggested to begin at about 1000 degrees C by X-ray diffraction experiments. The crystallite size and the crystallite amount were also estimated from the X-ray diffraction patterns. Electron spin resonance, nuclear magnetic resonance and Raman-spectroscopy were used to describe the structure of the material. In addition to these methods a combustion method was used to investigate the carbon and the oxygen contents.