HNO production is predicted by the reaction sequence NH 2 + NO → HN 2 + OH, HN 2 + NO → HNO + N 2 in the Miller mechanism for the thermal deNOx process. A search was made for the HNO molecule in the reaction system NH 2 + NO at room temperature using diode laser infrared kinetic spectroscopy to search for NH stretch absorptions of HNO. No HNO attributable to the deNOx process was observed. Sensitivity calibration measurements set an upper bound of 1% for the conversion of NH 2 into HNO.