Reflected shocks have been used to initiate reactions in mixtures of ammonia with oxygen, nitrous oxide, and nitric oxide which were diluted with argon. Final pressures were between 3 and 6 atm and temperatures before reaction were between 1460� and 2360�K. Speeds of the reflected shocks were measured and compared with the theoretical results for the cases of no reaction and of instantaneous conversion into equilibrium products behind the shock. The measurements confirm that certain difficulties exist when using the reflected shock technique with strongly exothermic reactions. Absorption spectroscopy on OH, NH, and N2O permits reasonable deductions on important mechanisms in the ammonia oxidation processes.