Chemical intermediates produced from the pyrolysis of hydridopolysilazane (HPZ) were studied in the solid state by multinuclear nuclear magnetic resonance and electron spin resonance. When pyrolysed at temperatures of 1200 degrees C, uncured HPZ forms a ceramic material with a composition of Si2.2N2.2C1.0, A series of HPZ-derived ceramics was produced using a number of different heat-treatment temperatures, varying between 300 a nd 1200 degrees C. Solid-state magnetic resonance data generated from this set of HPZ-derived ceramics elucidate important features of this complex transformation. Silicon atoms initially exist in two types of sites in the polymer, drop NSi(Me)(3) and (drop N)(3)SiH sites. Upon pyrolysis between 300 and 400 degrees C, the silazane cyclizes and cross-links, forming an intractable, insoluble solid. Increasing the pyrolysis temperature to between 400 and 600 degrees C creates a matrix that is partially inorganic; at heat-treatment temperatures in this range, many of the C-H bonds of the starting polymer are cleaved. Elevating the heat-treatment temperature to between 600 and 1200 degrees C generates a series of chemical structures with silicon in a tetrahedral site of the general form SiN4-xCx, where x = 0, 1, 2, 3, 4. No crystalline forms of Si3N4 or SiC were detected in the material prepared at even the highest heat-treatment temperature of 1200 degrees C.