This book is a report on the numerical simulations of methane/air, methanol/air, and methyl formate/air under different flow configurations; homogeneous system, freely propagating flame, and diffusion flame. A detailed review on different types of fuels, chemical kinetics of nitrogen oxides (NOx) formation, chemical kinetic mechanisms for the oxidation of methane, methanol and methyl formate fuels, as well as the thermodynamic and transport properties of species are presented. A chapter on the governing equations for chemically reactive flows follows the literature review. The numerical solution methods for these flows are presented in a different chapter. Three chapters of results and discussions for the different flow configurations have been incorporated in the book. For each configuration, a comparison of nitrogen oxides concentration profiles and other radicals that are dominant in its formation is made. In addition, a plot of major and minor species concentration profiles and temperature profiles is shown. Finally, the sensitivity of CH and NO concentrations to the reactions in the mechanism is presented.