Abstract-The high-temperature decomposition kinetics of nitric oxide have been investigated in shock-heated mixtures of NO, H2, and either argon or krypton. Initial NO:H2 ratios ranged from 1:2 to 2:1, with the inert diluent making up 90 percent of the test gas in all cases. Two high-speed infrared detectors were used to monitor the infrared emission from nitric oxide and water vapor. Calculations using a seventeen-reaction kinetic model indicate that the rate-limiting reaction for NO decomposition is the reaction of NO with atomic hydrogen,Math The chemical rate constant for this reaction, k1, could be determined accurately by optimizing agreement between calculated and measured emission records for NO and H2O. The Arrhenius-type expression which best tits the data from 21 shock tube experiments in the temperature range from 2400 K to 4200 K is Math.