The report describes an experimental and analytical research program conducted to provide information on the chemical phenomena involved in the conversion of air and fuel nitrogen to NOx. Under Task 1, Fuel Decomposition, early (preflame) reactions of fuel nitrogen species were investigated using one- and two-stage reactors. Inert pyrolysis experiments, carried out with several fuel oils, showed that the primary nitrogen-containing product was a tarry material that decomposed to HCN at high temperature (1100 C). Oxidative pyrolysis experiments, involving model compounds (pyridine, benzonitrile, NH3, and HCN), fuel oils, and coals showed that the primary products were NH3 and HCN at lower temperature, and N2 and N2O at higher temperature. Task 2, Combustion Kinetics, was carried out in a low-pressure flat flame burner. The formation of thermal, prompt, and fuel NO was investigated in CH4-O2-N2 flames doped with NH3 or HCN. In addition, the formation of fuel NO was investigated in a H2-CO-O2-Ar-NH3 flame. This simulated the combustion of a future low-Btu fuel containing NH3 as an impurity. HCN was shown to be a significant intermediate for all flames where the fuel contained hydrocarbon. Calculations were made during Task 3, Data Analysis, on the H2-CO-O2-Ar-NH3 flame using a detailed kinetic-diffusion model.