The thermal decomposition of coal was investigated in two reactor configurations - a heated grid apparatus and an isothermal furnace. The heated grid apparatus was operated in vacuo for the thermal decomposition experiments. Apparent heating rates of 10/sup 2/ /sup 0/C/sec to 10/sup 3/ /sup 0/C/sec were utilized while final temperatures varied from 500/sup 0/ to 1780/sup 0/C. A Fourier Transform Infrared Spectrometer (FTIR) was operated in the rapid scan model to follow the evolution of light gases from the coal during the devolatilization process. Structural characteristics of the parent coal and the tar and char products were also determined by use of the FTIR in conjunction with an elemental analysis system. Particular concern was given to the fate of fuel nitrogen during the thermal decomposition process. In addition to the study of the nitrogen evolution during the thermal decomposition process, the conversion of fuel nitrogen to NO during the initial stage of combustion was investigated by heating coal samples in the grid apparatus in the presence of oxygen. NO was measured by use of an UV resonance absorption technique. The isothermal furnace was operated at one atmosphere of pressure and at operating temperatures of 500 to 1000/sup 0/C. The FTIR was again utilized in the rapid scan mode to follow the evolution of light gases and to determine the relative amounts of light gas species evolved. The data from these reactors was utilized to formulate an operational understanding of rapid coal pyrolysis and a semi-quantitative model of the decomposition process. The FTIR was also utilized to examine the effect of various pretreatment processes upon the sulfur contents of the coal.